No girlfriends to tell... HELP

I dont even know where to start so here we go... I work for a daycare and my boss’s brother in law (he’s married to my boss’s sister!) confessed that he has feelings for me... we’ll just call him dave tor the sake of the post.

I started working for the daycare about 2 years ago and that’s when I met Dave he has a 6 year old that goes here as well. Dave has always been friendly but I just thought that’s how he was. He’s always hugging all the teachers that work here so I thought it was normal for him to be like that. The classroom I work in has a sliding glass and he always pops his head in to say hi to his nephew in my class. Well All of a sudden Monday this week he tells me I’m his favorite of course I was confused and was like what?? He proceeded to tell me that if he wasn’t a married man and I didn’t have a boyfriend then chuckled and stopped himself and asked me for my number and smiled. I didn’t give it to him of course. I actually like his wife and daughter plus I’ve been with my boyfriend 6 years and dont plan on changing that.

This week he has continued to come to the school to talk to the bosses husband who works here as well but makes a point to stop in my room and try to get me to leave my boyfriend he keeps telling me I’m bad and could have anything I wanted and that I can do better than what I have. Even while his wife is here. He will wait until she is busy helping with the school. May sound silly but this is a small family owned business and I’m afraid of losing my job because the whole situation. I’ve made it clear that I’m not leaving my boyfriend and he just keeps saying he’ll pray for me that I leave him... I really dont know what to do... I’ve been cheated on in the past and despise cheaters. I want to tell his wife but I’m too afraid of what will happen. I dont believe I’m the first girl he has tried this with either.

This has made my whole work situation very stressful and extremely uncomfortable especially when he’s here. I try to just occupy myself and seem busy with the kids to avoid eye contact or a conversation with this man.

Any advice or anything is appreciated!