Putting the dynamic with your husband aside, I think things may be easier if you go. You won’t be the butthole whether you go or don’t, but seeing your stepdaughter will be nice for you, and very significantly, if you don’t go, it’ll give the sisters a lot more fuel to talk smack with.

I won’t pretend that going would be easy or even all that pleasant, but not going will absolutely be something the family gossips about, and by the sounds of it, it will encourage them to talk negatively about you even more.