I was recently sexually assaulted by a male cousin going to the same college as me. Problem is, my mother's family has a tradition of meeting up for a couple of days after Christmas at my grandparents' property. I refuse to be in the same house as him but I am also not ready to share the reason with anyone in real life. 

Would I be the asshole if I asked my immediate family to perhaps consider not going this year, given that plans have already been made? I'd hate to spend the holidays alone, but if it would be an asshole move, the alternative would be to "fall sick" and bail on everyone.