Ex doesn't want me, because he has depression, yet when I'm with someone else he wants me around?

Hello there :)

In my opinion, if you see the guy is not an equal match for you, and that he only brings you negative impacts in your life, I suggest you to be firm with your decision to leave him. Because if you keep giving him chance to come back to your life, it will not make your life move on to a better state, but also you will not let him to recover from his conditions.

You deserve to be with someone better :) but if you still love your ex and willing to accept him the way he is, you need to be patient and keep on believing him that he can be 'healed' from his depression :)

Good luck :)
God bless you