EDIT: I forgot to add triggers of child death sorry

There's a ton of history and I'm bound to leave stuff out because I'm going to shorten things as much as possible (no, really, I tried).

Ex and I share two kids, 3.5yo and 1.5yo. I'm not going to bother to armchair diagnose him, but he's not well, and I'm not trying to be a dick when I say that.

You see, we lost a child. She was 3 months old and ex was working 3rd shift, which meant that even though I was awake most of most nights, I also had to be awake most of the day, too. To be honest, he could have been more involved in the day-to-day baby care even then, despite his schedule, but he wasn't. I didn't honestly care too much because I was living new baby bliss. One evening after he woke up I asked him to call off work because it had been 40+ hours since I'd slept, and I was crashing. He said they were counting on him to be there.

I slept between midnight and 2, woke to feed and change her, and then...nothing. I remember nothing, but I somehow didn't make it back to the bassinet. I had fallen asleep on my bed with her after her diaper change. He got home at 5:30, and at 7 he came in to wake me. I looked around, at the bassinet, and up to him and asked where the baby was. He didn't know. She had somehow gotten facedown on the other side of the bed, the side with the thick blanket. I did CPR until the ambulance got there, but she was gone.

We were both devastated, so I never blamed him for lashing out. I blame me, too, how could I hold him blaming me against him? We stayed together for years after, but they weren't happy years. I wanted to get grief therapy and he reminded me that I was the cause of her death, and had living children from a previous relationship when I was very young, so I didn't have a right to grieve. Still haven't gone, but I might someday.

He turned mean, too. Like really, really mean. He wouldn't hold down a job, so I worked and he stayed home. Except he couldn't stay home, because he couldn't handle the kids; he ended up bruising one of them with squeezes and I found out. They would cry and he would clench his jaw, grit his teeth, clench his fists together, scream incoherently (not exaggerating)... Some days it was honestly like living with a crazed half-animal, half-person rage-fueled banshee. He would scream, "I JUST WANT TO DIIIEEEE" at the top of his lungs, hit walls, etc. It wasn't fun. Less so for our children. One day the baby was crying for a diaper change and I was outside letting the dog go potty. Instead of changing the diaper, he paced with the baby in his arms and screamed until I got back inside. He refused therapy and all other means of help.

Anyway, things got worse. Every day he'd spend 3-4 hours complaining about literally everything that crossed his mind, and he never failed to remind me how each and every one of those bad things in his life was my fault. My fault for killing our child, my fault because I didn't tell him I was serious when I warned him one of my family members is a kleptomaniac, my fault because we didn't have money, my fault because he didn't have weed, my fault he didn't want to have sex because I didn't own any wigs or costumes, and on and on and on. Every. Single. Day. Every bad thing he said or did, he excused it by saying he was grieving. And he was, so I accepted that. And I deserved it, so I partially welcomed it.

I can't describe how I felt, though. I didn't feel quite human? Eventually I met an old friend one day at work, and we exchanged numbers. I'd never considered that I would actually cheat on someone, but I did. I experienced affection and kindness and understanding for the first time in years since my daughter's death, and it was intoxicating. I broke down and slept with him one evening because I wanted to feel something other than self-loathing. When ex found out (to be fair, I wasn't exactly hiding it--I look back now and realize I wasn't thinking clearly at all), he immediately blamed himself and dropped to his knees stating that he did this, he pushed me to this. We stayed together, again, but he told me that my actions didn't get a pass because I was never truly grieving in the first place, as her death had been my fault. Things were, shockingly, worse this time around.

Everything boiled over one day when he started in on me as soon as he opened his eyes, raged through the apartment and at me and the kids all day, and continued consistently throughout the day until after the kids went to bed. He was screaming aggressively at me at the top of his lungs and I finally snapped and told him to either stop screaming at me or I'd call the cops to have them talk some sense into him.

I messaged his family and told them that he'd gone off the rails and they needed to come get him or help me get him some help. He chose to leave that night and go back to his family's place 3.5 hours away. It's been almost a year. He's seen them twice since then. I set a condition that he had to go to therapy consistently and make some progress before I would consider getting back together. He's been to ~3 sessions.

When I was still under the impression that he was making some progress, I suggested the 3.5yo spend 2-3 days with him at his family's if he could find a safe ride back, and I mentioned if things went well we could work on doing a longer visit. He ran with this and booked a week off from work before he confirmed a ride.

But then one of his family members told me they didn't think it was a good idea to let him have her unsupervised.

According to the family member of his that I talk to, his anger has gotten worse. He gets so mad he drools now. He gets mad at his mom and says the most violent things to and about her (some of these he says to me about her). He threatened to slit her throat and watch her bleed out because she did a favor for the cousin he hates.

He still has yet to take accountability for anything or truly do any work to overcome his anger issues, and he's impulsive and often irrational. But he's also their father and I know he needs help, even if he refuses to help himself.

It's worth noting that we have not gone to court for custody. He's under the delusion that I need to make a decision about the future of our relationship despite him not continuing therapy, and when I don't respond to these messages he threatens me with custody court, stating that my refusal to work with him on our relationship issues would look bad in court and he'd get the kids.

When I said I'd prefer to him come here for the week instead he cried to the family member that I talk to. She then asked me to reconsider because he was heartbroken and he would be staying with his dad and wouldn't be unsupervised the whole time.

Genuinely, guys. Am I being an asshole here? I'm too far lost in my own forest to see the trees.

(Obligatory: yeah I already know I'm the asshole for cheating)