Problems with baby father

So me and my child’s father have been having problems since I found out he was cheating on me with his other baby mama. I left him but he still seems to try to get back together when I’ve even told him we should co-parent because I don’t have time to stress myself and the baby out and that’s what I’ve been doing since September. He recently called me and said I quote “what do I think he needs to do for things to be better”

And I told him I shouldn’t have to tell him what he needs to do better he’s a grown ass man he should know what he needs to do better! My question is should I have to tell him what he needs to do better or he should know what he needs to do better for us to have a better relationship. And mind you he lives with his other baby mama right now but trying to have a relationship with me 🤣.