Can you please help me understand and navigate this post-breakup interaction?

I don't trust relationship subs, so I want to ask in what I consider a much safer space.

Also worth mentioning: For my entire childhood/adolescence I was abused by my mother who had at least one personality disorder. And I may also be on the ASD spectrum, or I at least have issues that mimic ASD. For both reasons, I sometimes have a difficult time noticing when I'm being mistreated or taken advantage of. I have a hard time knowing when to put up boundaries. So I'm looking for some outside perspective from my peers here.

Here's what happened.... There's this guy who has been in my friend group for about 20 years. We developed a mutual crush and decided to try it out, with the understanding that we didn't want to damage our friendship or the group dynamic. So we dated for about a year, until I finally realized that there was a lot about him within the context of that kind of relationship that I really didn't like. He baited and fished for sympathy and attention, which I consider emotional manipulation. He seemed like an obsequious little yes-man who constantly agreed with me. Sometimes he would introduce a topic and express an opinion I guess he thought I would agree with, but if I didn't he would immediately switch and be like, "Yes, exactly!" lol He followed my lead on everything, and pretty often seemed disingenuous or downright fake. He bragged about having traits he very clearly didn't have. It just got really weird, and I was beginning to resent him.

So I ended things in December. We talked about it some, and agreed to continue as friends. And things have seemed mostly fine. There has seemed to be this huge issue hanging between us all this time, mostly emanating from him. He's been kind of mopey and clearly not as okay as he claimed he was. So over the last 6 months or so I've been occasionally encouraging and nudging him to communicate about it. I did tell him that I'm less interested in having a say myself, since I've processed everything and let go of all that, but I'm willing to listen and answer any questions he may have, as long as I'm comfortable doing so.

Well, finally he sent me a huge email. In it, he repeatedly claimed to be "confused" by my attempts to encourage communication from him. He said some of what I'd said "made him want to scream." He says he has "grievances." His email is full of quotes (of me) that he pulled from our chat history, many of them 6-12 months old, and he interprets them completely incorrectly in his email. So much so that I feel completely confused and flabbergasted. This on top of feeling overwhelmed by the sheer volume of it, and by the fact that he went digging through our chat history for "evidence" to throw at me. Throughout, he accuses me of doing the very things he did throughout our relationship, which I didn't do. The craziest one is that he accuses me of refusing to talk about the breakup, while quoting my own words at me in which I am bringing it up and encouraging discussion from him, which never came until now. It feels like an attack. I feel blindsided.

What insight do you all have on this? I feel like I may be too close to it for a very accurate perspective. But I also realize that all that really matters is how this makes me feel, which isn't good. Advice is welcome.