Stay strong and ignore him. You have no reason to talk to him. Remind yourself, when he tries to contact you, that you have a straightforward choice:
him v your children
HE - is a drug addict who is violent and abusive, blames you for his moods, makes threats, manipulates, controls, distances you from your friends, accuses you of cheating, FRIGHTENS YOUR CHILDREN. The list goes on.
YOUR CHILDREN - are children. Dependent on you. The people you love most in the world, and who love you most. They deserve to know they are the most important thing to their mum. They should feel safe and happy in their own home. They need to see a mum who won't let men walk all over her. You are their role model in life. What behaviour do you want them to see from you?
If you choose him (and by choose, I mean staying in any sort of contact with him, ever again) you are saying he is more important than your children.
You know he doesn't love you. They love you so much. Yet his opinions get into your head more than theirs. Please don't wrecj your children's lives, don't wreck your relationship with them (possibly forever) for a man who lies, is violent, angry, manipulative and doesn't care about you or your children one jot.