Need insight on this! Hones opinions please!!?

My ex and his girlfriend had a real bad break up recently. I guess he was needing a friend and consulted in me. We had met at Dennys to talk and I ended up getting a room and we had sex. He regretted what he had done and told his girlfriend. He didnt want to get back with her because of what he had done but she took him back. They are now back together and happy. He says he is going to marry her soon...what to think of this? To make matters worse i paid for the room and dennys!