Should I feel as hurt as I do?

On new years day we spent the day with my partners family. We were having a good time until they got talking about a friend of theirs, this friend has a girlfriend and my partner commented on how good looking she was and said that he would go with her if she wanted him too. This hurt like hell, I know he was joking around but its been 2 days and it has me on rock bottom. I suffer from depression and I have been constantly thinking about what he said, I now feel like I am inadequate, that I am not good enough the way I am. It is really getting me down and I have no idea what to do about it.