I would do two things. First I would talk with my husband about how it makes me feel so that we could handle this together. Second, I would have some boundaries about this situation. I can't tell you what boundaries I would have because I'm not in the situation, but I would have boundaries...i.e. my husband, myself and this boy meet somewhere away from my home (maybe at a resturant).
Like the others, I would give the boy a chance. He may need to talk to your husband about things so if private time is needed between your husband and him, I would give them the opportunity.