Hey Alexandria – You invested your time and energy in a relationship that was not healthy for you. You wanted to see the good in him and you overlooked the not so good. It happens to the best of us. We can never control what our partner desires or how they behave. We can only control our own actions. You were hurt by him because he chose another person. This is extremely painful to most of us. The jealousy comes from a sense of loss. You lost a person who you loved and invested time in for what ever his reasons (or lack of reasons) are. If he cheated on you while you were in a committed relationship, its his loss. He has only cheated himself on his own personal integrity. There will always be somebody more pretty or more exciting. There will always be a guy more charming or handsome. When we enter a healthy relationship, we realize that the love that two people share is far more beautiful and lasting than looks or personality. These things are temporary. Unless he changes radically, this will happen again and again. So really, you have lost nothing. You have nothing to be jealous of. As for the prom dress, let it go 🙂 Peace