Just remember, he may be feeling great for now, but he will not be for long. DVT is just the first thing to happen to him. He will suffer mentally and physicall for his drug use.
You my friend are doing great! You have cut off contact, you have went to a meeting. You are focusing on YOU....that is wonderful! So you had some pizza and a pity party? Who cares...hop right back up, dust off and see this for what it is...YOU ARE FREE OF HIM! Did you have love for him, sure. Does love mean we should be with that person...NO! It sounds like he does not love himself even.
It will not be you who is taking care of him when he is in the throes of the physical and mental damage HE IS DOING TO HIMSELF. And no, you are not to blame for the pain. It is a reaction you will work through. You did not cause it, you could not control it and YOU CANNOT CURE IT!
As far as his relationship, let her be a slave to his disfunction...bet it does not last too long! A user can pretend they have their life together and "court" someone but they show their true colors pretty quickly.
Chin Up....You can do this and you are not alone..we are here taking those steps with you!