To me, anyone who sleeps with you outside of marriage is "using" you

I absolutely disagree. He is using her as she is using him.

. If he doesn't have the decency to commit to you, he shouldn't have the privilege of being intimate with you - a privilege that was created by God to be enjoyed within the confines of marriage.

The fact that he is dating someone else and sleeping with you is a good indication of his character (or lack thereof).

He is not trying to use her, he is as mixed up as she is.

If he is confused and doesn't know what he wants, then he should have the decency and self-control to at least keep his hands off.  And if he truly loves you and wants to be with you, then why hasn't he broken off this other relationship? If he truly loves you, his actions would show it, and he would drop her like a hot potato for a chance to make things work with you.

When you break up with a person -- especially if you are the "breakee," it is natural to have intense feelings, to romanticize the relationship, and to long for the person. It is difficult to adjust to being alone. But you need to go back to why the relationship ended in the first place. If the main factors or reasons are still present and haven't been dealt with, then hanging in there and holding out hope will only disappoint you in the end. The same issues will creep in sooner or later. And now there is a new issue - infidelity -- that you would have to deal with.

My advice is to stay clear of this relationship! Break off the ties and move on! You deserve someone who is willing to commit to you, not use you and keep you hanging on a string, in hopes that he will eventually decide one day that he does want you after all...