AITA for not going on vacation with family?

All us “kids” are in our late-20s/early-30s. Parents still like us to do a family vacation and it does mean a lot to them. Anyways, this year my family wants to travel to Europe. Which I’m fine with except for the fact that my sister wants to bring her boyfriend who is a complete douche. None of us like him and he consistently destroys the mood as well as turns her into an asshole. Can’t imagine spending a whole two weeks with him/her and honestly don’t want to spend thousands on this because I know he’ll sort of ruin it. Told rest of my family the reason and they think I’m an asshole for this and making me feel guilty. AITA? Am I being selfish?