I am going to hate the family I'm going to marry into
Are you planning to do something to ruin the family?
Yes, I plan to do something bad to the family, but I also want to keep my wife happy. So there's that.
You should not hate your gf's family. She loves you and wants you to care about your new family.
I will just not stay in contact with her family.
But family is family, wouldn't you agree? How is your wife going to think if you already hate the people that she loves? I think it would be nice to try to get along with your wife as a mediator between all of you!