You know, Bellah- what it all boils down to is trust. Do you trust him- that he is telling the truth, that he wouldn't do this again further on down the line, that he isn't just hedging bets in case the grass isn't greener where he is heading? If you do trust him , then you have to decide whether or not you can live with
his terms, or whether to set your own. If you don't trust him, then you really should move on with your life. I don't normally like to give out relationship advice, but I will tell you that without trust, you do not have a healthy relationship.
This is for you! You're a great person with a lot to offer, and when the right person comes along, you'll be so glad you didn't settle!