I miss my ex boyfriends kids but not my ex boyfriend, IIN?

Of course! You have every right to be upset! I think the right thing to do is to get CPS involved. I know it's drastic, but you seem really concerned about their well-being, and this is something that is completely out of your control. You need assistance in getting them out of there and those are the people who can help. I'm sure things could remain anonymous as well, so their father wouldn't need to know that you were the person who called.