Thanks for the feedback everyone. When I asked the question my mind was in a non-sexual/non-AP related space so this will be what I primarily speak of.
As far back as I can recall my W would not set and maintain healthy boundaries with family members, our children and her friends. Of course this is my opinion so take it with a grain of salt.
Family/friends: Over the last few years (since DD:2019 edition) I have learned how my W's prepared to speak about so many things that I feel are not appropriate with others.
To keep it short, I feel if one has a concern/problem with your spouse you first take it to them and work on the concern where the problem, source and solution will ultimately be. It's not that someone can't get any feedback from a trusted friend or family member. But, to start, wouldn't you draw the line on what not to discuss with someone else at what you've not even brought up to your spouse yet? From there I could see some grey areas where speaking with a spouse about a concern is going nowhere and someone may scratch the surface of said problem a bit with a trusted person. But even then, there's a fine line where someone isn't seeking council but rather, they're just making the spouse look bad.
After DD, from time to time I would look through my WW's phone. During that time I'd not considered to look at her conversations with her girlfriends or family members as they weren't relevant to her A. At least that's what I believed until after months of trickle truth and gas lighting when it started to become more clear how treacherous she had been and was actively being with me. It was hard for me to wrap my head around what I was starting to realize about her and how she viewed me and our marriage. So I began to read those messages too and I saw how poorly she spoke of me along with just a lack of kind things to say about me. Her friends had nice things to say about me, but not her. Some of the things she would say were things I would NEVER speak about with anyone else. Not because they weren't necessarily genuine feelings I had. Not because you're harboring a spouse that's a criminal or anything like that. But because once certain things are said it will leave a lasting impression on someone and if it becomes gossip fodder, the damage to a spouse's character would be forever tarnished. It's a boundary that's placed to protect those we love from otherwise harmless idiosyncrasies we all have. Shoot, doesn't knowing you yourself have some unflattering traits and empathy for your spouse make you weigh if you'd want the same thing said to others if the roles were reversed?
In this particular case she presented me to a friend as a cruel husband demanding sex from her without a hint of concern for her recovering from a C-section. She'd had one 5-7'ish weeks prior and I'd not even hinted at sex or being hot for anything from her. It was in my mind that I'd wait until she showed herself active enough until I put a feeler out to her. After she'd began to exercise and do what I'd consider vigorous activities around the house I asked if she might be up for something. She said she wasn't and I kindly let it alone. Over the next few days she was quite active and so I expressed that I imagined she might still be sore downstairs but maybe she'd be up for some oral or an old hand-shammy. She straight up got angry with me and chastised me for not caring about her. She'd set a clear boundary with me that I would get nothing regardless of how active she was. I wasn't going to argue with her as it was a zero-sum situation from my side. This didn't stop me from seeing how little I was asking for from her. I let it go.
There I was in the middle of 2019 reading how she was presenting me to a friend of hers how awful and cruel I was. She made me look like a selfish sex fiend. She conveniently left out how active she'd been and how I asked for far less than anything from her downstairs. In hindsight I recognize that what she presented may be what she really felt that first time I asked her if she would be up for anything. It wasn't fairly represented, no. And yeah, it was way out of context. But still, why would she not have a boundary in place for such a topic? Wouldn't she know how badly this would affect my rapport and character in her friends' eyes and know that it may get spread to others?
Which leads me to family. It came to light that my W's SIL (her bro's wife) has repeatedly spoken badly of me in front of and to my W. I read it in text form and my W says nothing to defend me. It reads to me like tacit approval of whatever's said. I've accepted that her SIL is comfortable speaking of me this way because my W does it too. My W has no boundaries for others to not speak negatively of me, true or not. But I can see anger flair if/when I criticize (always as kindly as I can) either of her parents or her brother and she'll not remain silent. She'll defend them and debate with me over it. Not for me though.
Children:
Any given day I will see my W refuse to set or enforce boundaries with the kids. When I've asked her why she has such a hard time simply saying "no" when "no" is the appropriate response, she redirects that she does say no (about something else unrelated) and avoids what the real subject is. It's not that she's never said no. It's that it supposedly happens but only when I'm not within earshot.
The kids have unfettered access to sweets in the kitchen and they act on that as any child would that hasn't been told to ask first. I've set a house rule that they must ask first but I am not there as much as she is and she doesn't enforce the house rule. So I end up looking like a mean dad because I don't want them to spoil a healthy appetite, be wired all night and also want them to learn that they'll not always get what they want in life (I don't want to raise entitled brats).
My W has the hardest time with our 3 YO (allllmost 3 YO now) screaming and freaking out while hanging on her until he gets her undivided attention or what he wants. While he's with me, he behaves (as much as a 3 YO can) and listens to me. He's not scared of me...quite the opposite, we wrestle around and play really good. I tell him I love him, hug him countless times a day and we get to enjoy each others genuine smiles constantly. My W does the same but she struggles to contain/control him. It's not about love being there or not. I've tried to kindly explain that he behaves for me because he has learned that when I say something, I mean it. I understand he's 3 YO, set boundaries that are appropriate for a 3 YO and then I consistently reinforce any boundaries set. I've encouraged her to do the same but I feel as though my doing so irritates her because I am not with the kids as much as she is. By default, mom knows kids better than dad does....or something like that. (again, just my own feelings)
Bringing it to the A's:
She's admitted that she entertained the last AP's texting/calls because of "not wanting to offend or make him feel weird by saying something to me or telling him off" 
(Admittedly, she just recently said that she did it because it made her feel good). I asked her if instead of beginning to flirt and shower her with compliments, he had begun to say inappropriate things about one of our kids, would she have responded the same way about not wanting to offend or make him feel weird by telling him off or telling me. She exclaimed how quickly she would have shot him down and told on him. I asked why she'd respond that way, and she said because it'd be way inappropriate and inexcusable. Me: "Ask yourself W. Why didn't you feel his advances on you were just as distasteful? It's all about boundaries. The boundaries you've set do not protect yourself or our marriage. Why?? Why is it so hard for you to set boundaries that protect US??"
Folks, don't get me started on the boundaries I've lived with for 20 years.
When I weigh how few boundaries she has for her family, friends and, yes, the AP's, against how forceful she is with boundaries with me I am left with a few ideas. The first is that it's less about the ability to set boundaries properly and being more about if she likes someone or not. The next is that it's something she's never conceptually understood. Maybe she sees boundaries as something for bad people and good people are boundless?
I have a hard time empathizing with or understanding her on this (again, as I perceive it). To me, boundaries are neither absolutely good nor absolutely bad. The measure set, when appropriate, is good and when poor, is bad. There's the rub. At the core, it's really a balance problem I suppose and a lack of appreciating the underlying purpose. It's a measurable expression representing what one loves and what one hates.
I've discussed these parts of our life/history with my W. I don't think she gets it. I see her look at me while I am speaking but I really don't believe she understands what I am saying.
[This message edited by NotMyFirstRodeo at 7:11 PM, Friday, October 15th]
