Ah, the million dollar question! I went through 10 years of running away from me, but found blame in everything around me, including my DH.
I only realised once it was too late, me and DH split last year. I spent too much time in the woe is me phase and only realising recently, to find xDH had moved on.
I'd suggest showing him this thread. He may well dismiss all of it, but I don't think there's a lot you can do. He does truly have to fix himself.
Here's a story that might help. 10 years ago xDH, myself and 2 DS moved 120 miles up the country from London. We did this for the sake of our children. They have thrived beyond my wildest dreams, for which I am incredibly proud.
Me, I 'lost' my identity. I had no friends, no job, no life. My depression manifested itself through anxiety, I couldn't stand in the school playground anymore, I couldn't stand the thought of anyone talking to me.
I went to the doctors, got told it was a blip and was prescribed beta blockers to slow my heart rate.
I got a job, struggled through, all the the while trying my best to hold it together. I had moved and done the best thing for my boys, what did I have to worry about!
Fast forward 10 years, 5 house moves, multiple AD's, many arguments with xDH, arguments with myself, living in denial.
Today, I am a single mum living in rented accommodation. Eldest DS has self esteem issues, youngest DS doesn't want to talk about 'stuff'.
My XH has moved on. I am happy for him. I am not happy with what I let myself become, though in a better place recently, thanks to a good GP, but I can't undo all that happened and that will live with me forever.
I feel and share your pain x