Yes, you are overreacting. Just because you're married doesn't mean it's reasonable to restrict your husband's social interaction with half the world's population.
Listen, basically you're not comfortable with your husband having female friends because in theory it would be possible for him to become attracted to them, right?
Well, I'm bisexual. In theory I could become attracted to ANYBODY. Would it be reasonable for my husband to tell me he doesn't want me to have ANY friends, or would that make him a controlling jerk trying to isolate me from other people?
And how is it REALLY different for you to try to isolate your husband from all women?
You have a nasty case of jealous paranoia here. If you value your marriage, I suggest you find a way to get over it.