ADHD leading to divorce

Recently in a "moment of clarity" my husband of 6 years (who was diagnosed with ADHD about 3 years ago) has decided that our marriage is too difficult and that despite the fact that we got along before- we just don't "click". We've known each other since childhood, so this is difficult to accept. Throughout the marriage there have been struggles with his impulsivity disorder- especially when it comes to private relationships with other women (which have been limited to communication and nothing further, but hidden and lied about nonetheless); then the subsequent issues with accountability/ remembering/ explaining his motivations.

In the middle of last month, we got into an argument (about him not realizing the effects of his actions) and he moved back into his mother's house (and has not come back). The downside of this is that we also found around the same time that I am pregnant; he was very excited about that fact until we started discussing how it would change our day to day routine (work/school/attention paradigm).

Medication wise- my husband has been on and off of medication the entire time, never really sticking to one more than a few months. Recently switching to adderall and taking it roughly every other day, until he stopped completely about a week ago. He refuses therapy (although I'm not sure the advice we've received from our therapist has been "ADHD marriage" realistic; mostly reinforces how "wrong" his behavior is)... he refuses to even find another therapist.

At this point, I've just started reading the book about how ADHD effects your marriage- I see that he and I have had a significant parent-child dynamic in our relationship. I can see how this has deteriorated our marriage.

No matter what discussions I try to have with him- I'm getting the stonewall response. "I can't be with you- I'm ready to start a new chapter. We argue too much" is the most I really can get. Despite my best efforts to discuss this, showing examples to the contrary, I think it's just further polarizing him. Right now, he says that he feels calmer and happier (which is probably true, as the only responsibility he has to anyone right now is to himself to go to work- no one is placing any demands on his reliability or attention otherwise). I realize that pushing him to acknowledge what is happening and the reality of how his symptoms have shaped our interaction is just stressing him out.

I know that his ADHD symptoms have caused a lot of the issues that we have- but instead of him realizing that- the target is instead on my back. He just wants to no longer be my husband and to deal with me as little as possible. He wants to get a divorce as quickly as possible; after only two weeks of separation decided he wanted separate bank accounts. Rather than having a conversation he says "when can I expect your lawyer to serve me". Most conversations are extremely adversarial, or he is defensive before it even begins- shutting the whole communication down from the start.

Any thoughts or experiences that any of you have would be extremely helpful. I am beside myself at this point.