Patti, take it from someone who's been there: remove yourself from this situation now. Regardless of your feelings for him, or his feelings for you, it's bad Chick Karma to be involved in ruining another woman's relationship.
And even if you wanted to take that risk, you'd be helping him become the kind of man who you wouldn't even trust! (If he'll do it to her, then there's nothing to stop him from doing it to you too.)
If he is now confused about his feelings for his girlfriend, then he should resolve those on his own, without any external distractions (i.e., you). If that results in him leaving her, and then after further reflection and some time to himself he decides he still has feelings for you, then that's something you both can deal with then.
For now though, you need to steer clear of him - a minimum of two months with absolutely NO CONTACT goes along way toward negating the bonding effects that sex can have on a woman, and so you'll probably find your own perspective is in a much better state at that point.
Good luck, and stay strong!