Hi. Sorry about your family I come from a terribly dysfunctional family as well. It is your decision to make. But maybe by inviting you this is their attempt to reach out?... I don't know them so I can't say for certain but maybe they are just not emotionally intelligent. If I were in your situation. I would go to the party. But only plan on staying for like ten minutes. Let them know you can only stop by for a short time..use the baby's schedule as an excuse if you need one. So that way if you are having a horrible time,you have already set up a clear out that won't appear like you are hurt or upset...and who knows? Maybe you will have a wonderful time and then you stay longer?! I say hope for the best, but prepare for the worst. If you show up without any expectations then you can not be let down. And every great once in a while people can surprise you!