** My unborn sons grandfather is trying to sleep with me**

My babys dads father has been messaging me telling me how beautiful i am ect. I thought it was cause he knows ive been feeling down about myself lately during my pregnancy nd was trying to make me feel better. He told me he wanted to tell me something but couldnt because it would get him into trouble. I thought it was something his son said ( my babys dad ) so i told him to tell me. He told me he cant stop thinking about my lips, how he wants to kiss me and then he got very sexual with what he would like to do. I dont want to completley cut him out because he is my babys grandfather and I also dont want him to get mad at me and spread false information. I have all of the messages saved in case that does happen but I dont know what to do. Today he told me hes definetly going to sleep with me. Right now hes the only person I had for support during this pregnancy on my childs dads side of the family so im trying to tread lightly. If it was anyone else id tell them where to go. Someone please tell me how to handle this!!