How do I balance the 180 with protecting my emotions and detaching from my WW, and at the same time be able to communicate my pain?
Second part first, what is the positive outcome of communicating your pain?
I suggest that you focus on something like 'What do I need to do to heal?' Communicating your pain may be part of that, but it's only part.
IMO, a WS can't do much about the BS's anger, grief, fear, and shame - resolving those feelings was all up to the BS. OTOH, I can understand that letting one's WS know what I was feeling was important.
I did that naturally.
When I was feeling something, I told her (and told her with the emotion showing.) My goal was to release the feeling. Releasing feelings helped. Using feelings to rub WS's nose in her shit, not so much. I know shaming my WS didn't help, because I did my share of it.
First part 2nd, if R is on the table, the 180 is not for you. The 180 minimizes communication. Finding out if your WS is a good candidate for R requires maximizing communications. That is the only way to find out if your WS is a good, indifferent, or bad candidate for R.
The 180 is useful if you find she's a good candidate for D but can't detach. Right now you need to build yourself up and communicate or - given your W's behavior - move to D, but see below. I really dislike the original 180 list. I recommend reading https://www.survivinginfidelity.com/documents/library/articles/discovery/the-simplified-180/.
One part of the 180 is aimed at finding and enhancing your own strengths. That part is something you'll need to do in any case. A good IC can help your with that, if you find that difficult.
How do I let myself experience emotions and get depressed for a few hours when I get a trigger that brings back all of the emotions and not feel as though being an emotional wreck is feeding my WW’s re-writing of our past fantasy that I am "emotionally immature"?
Stop thinking about your W. Do what's best for you. WRT emotions, feeling them - letting them flow through your body - is the quickest and healthiest way through them. If you stop yourself from feeling, you stuff them, and they'll come back and bite you at a bad time.
It's a lot of painful work. It's totally unfair. But feeling your emotions is the fastest way through them.
DDay was two months ago. My WW started IC one month ago. My WW is not remorseful at all. I would say that due to her anger of perhaps realizing how bad she messed up has lead her to insane blame shifting and being angry and me for the smallest things, as well as her purposely trying to get me angry so she can justify her actions and make me the bad-guy in the marriage.
I was in shock for 3-6 months after d-day, and I I'm not alone in that.
One one hand, you are at the very beginning of healing. The less you let your feelings flow, the more work you have ahead of you, and the farther from feeling healed you are.
One question you that faces you is: Does your W show any sign of changing, or will she not change until it's too late? The sooner you answer that, the better for you - but it can take a long time to get a valid answer.
Then you need to answer, 'How long is 'too long'? Alas, you have to answer that for yourself.
Are we still in the beginning stages of this?
Absolutely. Totally. You are at the beginning beyond a shadow of a doubt.
Am I unrealistic to expect my WW to take accountability and be remorseful and realize what she has really done this early on?
Well, no, but ... it takes some WSes months to start changing.
Why did she start IC? If part of her motivation was to change from cheater to good partner, or if she gets to that point quickly enough for you, R is possible. Otherwise, D is likely to be your best bet.
Do you have requirements for R? If not get some, and see if she's willing to agree to meet them. If she is, again R is possible. If not, D is probably your best bet.
My reco is to make your healing your primary goal. Let D or R come from that. If your W continues to minimize and/or blame-shift, though, you'll probably need to split to heal yourself.