I would caution you not to use your WW's BPD as a crutch. Crutches are a drug for people who can't handle reality, to twist that old phrase.
Even without infidelity, being married to somebody with an illness such as BPD (or alcoholism, etc.) is very, very difficult. It's pretty much a constant lifelong battle. Possibly noble in some ways - an extreme example of the "worse" part of "for better or worse" - but also possibly co-dependent to the point of being dysfunctional and self-defeating.
When you add infidelity to the mix, it is a slippery slope toward toxic co-dependency. The threesome is a perfect example. From what you describe, your WW had a long-term EA/PA with your friend. WAY inappropriate, for years, carried on in your home, in your close social circle, immediately in front of your face. As sadistic and sick as any thread I've read here on SI. It is wildly inaccurate, never mind unfair to you, to now try to retroactively blame it on the BPD. BPD tends to manifest itself in episodes. The prolonged infidelity with your friend was a continuum of behavior that your WW indulged for years. As you note, you were the unwitting brunt of their private three-way joke, and your WW repeatedly allowed you to be put in that situation. That's not BPD, my friend. That's nothing short of outright contempt for you. Further, as you note, the three-way was about the man, your friend. Maybe his wife found it hot too, but it was about giving him the double thrill of casual sex with somebody new, plus naughty, illicit sex with his friend's wife, in the presence of and with the participation of his own wife, so the three of them could chortle about it amongst themselves whenever the four of you were together.
The foregoing is offered not to inflame your anger, but to point out what to me seems obvious, but from your posts seems like it might be mired in the muck of all of the stuff you're dealing with at present. I would caution you to NOT let your WW get away with dismissing her prolonged bullshit as "that's the BPD talking". It's not. It was "that was me, being a shyte person" talking.
Further, this whole "I've been faithful for [blank] years," that's a red herring. A diversion technique. A meaningless tautology. A million cheaters resort to the "I've been faithful since the last time I cheated" schtick. "I never cheated except when I did." Or, "I haven't cheated since the last time I cheated." These are all versions of the same statement.
Your question should be: have the last 9 years been the marriage of my dreams? As to this, I would caution you again. She starved you for affection for decades. In recent years, she's been throwing you some scraps. Like any starving man, a few scraps of rotten meat taste like the most delicious Filet Mignon your imagination could conjure. Don't fall for it.
I saw a documentary recently of a woman who was kidnapped, tortured, raped, and held hostage for years. Eventually she succumbed to the Stockholm Syndrome so hard that the man and wife who kidnapped her were able to let her live openly in their home, as part of their family. The man even took her for a visit to her parents and siblings for a holiday dinner, and she willingly returned with him. This, even though at night they still locked her into a coffin-like box beneath the bed. Her "normal" was so warped that the simulacrum of normalcy and kindness offered in bits and pieces to her seemed like wonderful gifts.
To this end, here is what you say:
The first is that we moved over an hour away from that area, from the city to a rural community where there was very few people. Second, she left all her friends behind. I was already reclusive due to my PTSD and my best friend and his wife were really the only people I talked to. She started isolating herself as well because of where we lived and her own depression. Third, she stopped drinking, going from every week to maybe a few drinks a year. These are things she did on her own. She has worked for me, so when she gets to and leaves work, I know for a fact due to our GPS report system. She comes straight home and goes straight to work. Since we still have a nearly 2 hour work commute, its hard for her to hide it. Fourth, our relationship got a lot better. She was becoming less standoffish, becoming more affectionate, and her demeanor towards me was better. She did not appear bitter. We started doing more things together as a couple such as scuba diving, going on cruises, and just hanging out as a couple.
Let's untangle that:
1. You moved away from people and she's now a recluse.
2. She doesn't get sauced frequently like she used to.
3. She comes straight home from work.
4. She's less standoffish (meaning, she is still standoffish, just not as much as before).
5. She can create the appearance of not being bitter.
6. We've done some "friend type" stuff together.
Man, seriously? Is that what you've got after 9 years? What your benchmark should be: "She frequently initiates amazing sex with me. She constantly does little things for me around the house. She surprises me with notes and such reminding me how lucky she is to be married to me. She's even suggested bringing in one of her girlfriends and arranging a three-way for us."
Man, my strongest possible advice is to separate from your WW and gain some perspective. Your approach has been to burrow deeper and deeper into the muck, to become increasingly granular. You're not seeing the forest for the trees, as they say. Back away. Clear your head. Get a real vision of what a healthy relationship should look like. And walk away from your WW unless and until she comes running after you with an actual healthy relationship on offer. I reckon, by the way, that she lacks the ability to do this. She has been accustomed to treating you with contempt and cruelty for so long, I don't think she can figure out how to offer you compassion and love. That's just my opinion, of course, and it's based only on the limited details you offer. But the over-arching thing I think you need, more than anything, is distance and separation from her.
As to one small point:
She claims she regretted it the moment she started to drive home and it was never discussed between them again.
This is cheater 101. Almost every cheater has said some version of this. It's complete bullshit. The first tool in the cheater handbook is to try to minimize the extend of the damage they have caused. For some reason, cheaters seem to resort to the old "I regretted it right away" as an attempt at this. Tell her that if she says this, or any version of it, again, you're leaving. It is a flat-out lie.
[This message edited by Butforthegrace at 12:28 PM, Friday, December 24th]