Congrats on getting out of that relationship. Been there, done that, it's not your job to help him heal. Anything of his is not your responsibility from the day you said "It's over". From now on, the only thing he will hear from you should be "I'm sorry you are upset, please call the crisis hotline/your friend/ your mom/ whatever to talk about it. I will not discuss this with you any more." And yes, even if he threatens suicide. Just, you know, call the police on him if he actually threatens it. Log and record all interactions in case he gets dangerous. Lock all social media accounts. And go on enjoying your life free of him. Hopefully, he gets the message without needing any drastic measures.
"My school is the doubt in your eyes." - Tito Mukhopadhyay