Surprisingly devastated

I'm writing here before I go to bed. I'm alone in my home with my two kids as five weeks ago my husband with ADHD, medicated with adderall extended release told me that he finally "understood" what I had been saying for years and that we are incompatible and fight too much. I HAVE said that I'm going to leave on innumerable occasions IF things did not change (I always found that I could get him to hyperfocus on saving our marriage/relationship if I got REALLY angry with him, which is to say *threatened* him with divorce). I have since realized very clearly that what I was trying to do was get him to do something about his ADHD AND tell me he loved me. After we got married and began to have children (we have two now, one is five months old), he receded so deeply into his head we rarely spent any time together, hardly slept in the same bed, hardly had sex, basically did nothing like what we did in the beginning of our relationship. It's amazing we even have children, to be honest! Don't get me wrong, we've been fighting from the beginning, he just always made promises about changed behavior (before we knew about ADHD and how significantly it can affect a relationship) and I would take him back because, boy, he sure knows how to woo a woman. That's how he got me in the beginning, even though there were many, many red flags, including the fact that he could barely stand to listen to me talk (without moving, yawning, glancing at other women/things, interrupting, it always looked like I was killing him by speaking) and this was before we'd had 6 1/2 years of resentment built up. And yes, along the way I have acted in ways that I am embarrassed about (yelling, criticizing, putting his stuff outside once early on b/c he would not leave when I asked him to (he's also a stubborn guy), throwing pillows and on, and on, and on). But as more responsibility landed on my shoulders over the years (he has a spending issue): care for the children (night and day), bills, budgeting, appointments (for everyone), all deep cleaning (he likes surface cleaning when he feels like it), folding laundry, maintenance of the house, maintenance of the cars, maintenance of friendships) I became more and more stressed to the point that in the last year as I was pregnant with our son and staying home to look after our 2 year old, as well as work part-time and go to school part-time, I honestly thought that I might die young from stress. Small example: I begged my husband not to smoke or drink alcohol the night before we had our life insurance appointment where they draw blood, but he still did. Our premium went from $20 a month to $80 month. This kind of thing happened all the time. He was on and off his medication all year (school year) and would get mad if I pointed out the positive effects of being on the medication (more focused and organized and attentive). He said the medication made him feel very cold (he also tried Vyvanse, which made him manic and very physically ill) and I suppose, considering he has asked for a divorce, it makes sense. After the baby was born in April, he receded even further from the family. It seemed like he didn't care for our son at all (he was very fussy and hard to care for) and he just spent most of his time with his band (he is an amazing musician, this is one of the places that his genius resides). I was angry a lot because of course my *load* had just increased and my husband seemed to be receding more instead of helping more. In any case, we took a trip to visit my extended family for the first time in our relationship and while we were there had a pretty tremendous fight and didn't connect much during the entire time. He returned four days early and when we got back, the next day he asked for the divorce. He seemed very unmoving. His parents came down, shocked by his sudden decision. I was shocked too. In some ways I thought maybe it was for the best, though wierd timing (he had just finished grad school and gotten his first job, so we were finally making head way. Note: I supported him in finishing his bachelor's degree at age 34 and getting the master's degree. He does great in his own life when he has support). I was just about to start a nursing program -- it was my "turn" so to speak. Anyway, he was unmoved by his parents and by me and by conversations with a friend who is a pastor. It just seemed so wierd. I noticed his ring was off and an alarm went off in my head. And then yes, I uncovered the fact that he had actually met a new woman (a younger woman, 24) out at a show on some evening and had fallen for her. He now claims that she has nothing to do with his decision, that he had been gone from our marriage for some time. He is in the midst of a whirlwind romance with this woman and has already committed himself to being her "partner" and helping her heal from the loss of her husband and unborn child three years ago. They are in love. I unfortunately have already run into them in our town (it is too small for divorce) and it was like a hard blow to the stomach. They looked like newly weds. It reminded me of when he and I were first dating. It hurt immensely. I thought I would throw up. I could not fathom how he could go from being part of our family three weeks earlier, to a new relationship with that much intensity. I wrote to this woman to ask her to give us a chance (I guess I thought maybe she didn't know that he had a wife and children). She wrote back a horrible note. Apparently, my husband has told her that I am emotionally abusive and that it was a terrible 6 1/2 years for him. I am devastated by this. It's like the last 6 1/2 years of my life where I have worked myself to the bone trying to hold everything together all because I believed my husband when he kept saying that things would get better when the current stressful thing was over (undergrad, grad school, new baby, etc.). It just never got better for us but we had many amazing times together and I have seen a wonderful person under all the distraction and chaos. I'm jealous because I know this woman is experiencing hyper-focus and I miss that so much. I don't miss the guy that hated listening to me, that I walked on egg shells around b/c who knew what mood he would be in, the guy who prioritized himself always, and who felt passively controlling of everything. I would beg for his help and in put with everything and he would never  find the time but then he would be angry at me for not including him or for the fact that there was no food in the house that he liked (help with the grocery list then!). I miss the fun guy, the friend, the one who was there with me during the labors of both of my kids, the energetic, political, venting, fast talking mocha drinker who has excellent taste in music and whose music I have always loved. I cannot believe that I have been cut out of his life, completely and utterly. He has not abandoned the children fully but he did give up on me. I can't believe how devastated I feel, especially to know that some other woman is out there getting his hyper-focus. I can't believe that after all this work to get him where he is, he is leaving me. And with the kids and no income! It just seems insane. I just really need some support and clarity. What is happening? Did the medication he is taking help him see more clearly so that he decided we truly aren't compatible? Has he really found his soul mate in this new woman 12 years his junior? Am I actually a terrible person for reacting with anger to all the years of stress and over-responsibility? And what a shock, I can't get him to help me sort out the divorce settlement outside of court. I keep asking and asking and asking for help but it's been days of no response. Any thoughts and feedback would be so appreciated. My friends and family can't understand how I still love this guy who has now added infidelity to his list of harms and his incredible coldness in the process has been so hard (though he has let me know three times that he still loves me and misses me, very difficult and confusing to hear). But everytime I read about ADHD, I know that is the center of our marriage. He, on the other hand, is tired of hearing about ADHD and he thinks that in the end, I don't like who he is and if ADHD is him, he is right.