Is it too late

Hi,
I have just broken up with my ex 5 weeks ago. We have been tog 15 years and have 2 children tog. This came as a massive shock to me out of the blue. We hadnt been in a great place as a couple disconnected,no communication just living as friends really but I hadn’t realised it was this bad. Our past is long and very painful, all started a few yrs ago death of both his parents my sister on drugs endless emotional family issues that broke us both we both pulled away me more so I couldn’t deal so I shut him down no intimacy I became depressed and we both became unhappy
Until he finally said enough. He umed and arred for weeks after telling me he said he didn’t have it in him to fix he is angry hurt at how I pushed him away. He said maybe in the future we may get back tog but right now he is done. He started talking to a friend who is 11yrs younger with a 6mnth old baby…before making this decision. He moved out a week later I found out they kissed it has now been 5 weeks I have done all the crazy which has only pushed him further to her. He now says we are done forever and he wants to sell our house and starts his new life without me and he is seeing her and there is nothing I can do about it I need to back off and get over it he never wants to be with me again. no contact rule is hard we have kids he comes to see them but we always end up back in the same conversation that get nastier by the day… please help