He enjoys getting attention from his ex girlfriend who had a child by him. His contact with her is going to continue. Don't blame her. It happens because he lets it.

Do you and he have a child together? If the answer is no, I would advise you to think seriously about getting out of this marriage. This is not a good marriage. I don't think he is capable of having a good marriage.

If you don't have a child by him, please consider making sure you don't get pregnant by him anytime soon. This is not a good situation to bring another child into.

I don't know what you mean by saying you are co-dependent. Sounds like you have very good reasons for not feeling happy living with this guy.