I think you should tell him that you are very much in love with him and don't want him to marry the other woman, but want him to marry you.

Now, that probably won't make him break up with his fiancé and run into your arms.

What it will do is bring the truth to a head.

Then you can tell him that you don't want to pretend to be his friend and hang on, waiting in the wings, watching him get married, hoping that will fail and he will run back to you.

He is toying with you by telling you he still loves you. He also want you waiting in the wings. Maybe he'll get a little action on the side. You deserve better than that and you ARE worthy of love for real.