Should I tell my friend that her husband is gay?

This whole thing is a HUGE mess. I do daycare for some of my neighbors. Because I only watch a couple of kids my family has become pretty close to most of the families. Over the summer one of the fathers of a little girl i watch not only hit on my husband but propositioned my husband for . My husband is in no way phobic and neither am I. So to us it was just a hurtful situation. For me my friend hit on my husband- I was taken aback and totally hurt. Not knowing what to do and not wanting to hurt his wife who is completely clueless, I did nothing. Well except we blocked his number from our cell phones and unfriended him on facebook. He went nuts and called my home phone and stopped by my house numerous times, but I blew it off until my husband decided to tell him to calm down and that we would just keep watching his daughter and my husband would not tell his wife. I have gone on with my business and just not spoken to him when he comes to get his kid- plain and simple. You would think he got the hint, he hasn't! Over the last month and a half he has consistently tried to talk to me, even at times getting what I consider catty with me. Now after months of thinking it through I still don't know what to do. I feel like I'm being a horrible friend to his wife- who has been nothing but nice to me. I don't feel like it's my job to tell her that her husband is gay, i think he needs to. WHAT DO I DO? I am open to any knowledgeable advise and I'm curious- Has anyone gone through this before? Do you know anyone who has? Thanks in advance.