I think it is an error to see this relationship as one where you’ve been used. While I understand how you could come to that conclusion, there is another way to look at it.
You were in this relationship for a reason that may be important to explore. Perhaps you needed to feel useful to someone so needy, possibly the intensity and long-distance substituted for intimacy, maybe you needed to learn how to establish a boundary. Whatever it was that drew you and held you to the relationship is on your side of the fence. As Eleanor Roosevelt said, “No one can make you feel inferior without your consent.”
You were in this relationship for a reason and whatever that reason is has changed. Him getting healthier and having a relationship and bothering you less is exactly what you’ve wanted. So it is curious that as he has changed, you are feeling used rather than relieved and happy for him.
It is time to move on. I do not think you need to do anything about cutting him out, blocking him, or confronting him. Your work is for you to recognize the dynamics that brought you together for mutual benefits have changed and that you are both less important to each other than you have been. Don’t give him any more a priority than he does you. If he connects every few weeks you can be casual about the timeline you respond. He hasn’t done something wrong; he has simply moved on, which is now important for you to do.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral