I am 21 years old and have been with my boyfriend for eight months. This is the first relationship I have ever been in; we had sex only a couple of days after we met and I have been with him since. Obviously I trust him and love him and we have a very healthy relationship, but I have known for a while now that prior to meeting me, he slept with 15 other girls. I have a history of depression and ever since he has told me I have started to feel really horrible about it all - I never thought it was something that would ever bother me, as I have friends both male and female who are promiscuous, but I feel so much differently about it now that he has told me. I feel that it upsets me a lot and I don't know why and I can't understand it. I have tried to talk to him about it a lot but he won't open up to me and I don't know what else I can do.