Morning, I read all your story last night. You seem like such a decent person that only wanted what was best. It so sad that some people can’t find their way. My ex partner, had periods of being ok, but it never stopped me wondering when the next time may be, or what mood will come the day after. He used to spend days in bed, either on a come down or sleeping now life away so he didn’t have to get up and face it all.
When I think back I was already alone. And constantly down and upset and angry inside. He used to say things about my parenting, that I do too much for my children and that my son had put weight one (he 10 and got a totally normal BMI) no big for his age at all. He has such a terrible relationship with 2 of his own children and has one child he has nothing to do with despite my encouragement. You sound like you have done everything you can to want a better life for your ex partners kids.