Sounds like it might be a good time to think about what your goals are in therapy and whether you are currently making progress on them, or how this therapist is helping you to make progress. If the attraction is helping you to break an old pattern of relating to men, then that might be worthwhile. But it sounds like this could lead somewhere painful.

It's good he has supervision. I'm surprised you have access to his supervisor, though. My T has one and I have no idea who it is.