oh i get it alice, the naked guys at whiskie's party reminded you of your ex. well my dear, if he wanted you he will be partying with you. don't do it.
Realise this is half an hour later, and a lot may have happened, but stay cool sweety. If he's your ex, he's your ex for a reason. It's really really tough, and if you really want him back then do it, but don't be in contact just because of the pain, the pain goes a damn sight quicker if you don't have the contact. And you can go on to meet someone wonderful.