Trust is a two way street. My guess is that he doesn't trust you because he has issues about his own trustworthiness.
It's About Him, Not You
I think that you should explore his feelings that clearly go beyond jealousy to something deeper and more insecure in his own life. In other words, I think this is really about him and not about you.
Friendships Shouldn't Be Restricted
I don't think it's fair to restrict friendships to same-sex only. What if you started to be attracted to women, too, then would you not be able to have ANY friends??
Friendships are your own. They are private, personal and really none of your husband's business. If he can't handle that boundary, then there's another issue you two should be discussing.