What can I do??

Ok so this is not pregnancy related but I need advise!!!

There’s a parent in my daughter’s classroom how just won’t stop staring at me and it’s been freaking 3 years, since they were in kindergarten now they are in 2 grade ( my daughter is in a dual language class so all the kids will be together until grade 5th) and I don’t want to keep dealing with this I told my fiancé and he said to put a stop to him and if that guy said something or just don’t stop then my fiancé will do something about it but the thing is I’m kinda shy and now that I’m 26 weeks pregnant i just can’t tolerate it anymore this needs to stop I find it soooo disgusting and very disrespectful specially when he knows I’m pregnant and obviously in a relationship and I’m sure he has seen my fiancé because sometimes he comes with my to our daughter’s trip or when he picks her up from school!! What can I do should I tell him something? Should I talk with the teacher or go to the office and report him???

Thanks