Yes, you done messed up big time with this one. As far as "Am I The Asshole?" threads go, this one was just glaringly obvious. You're going to bail on your boyfriend in arguably one of the toughest times of his life for a vacation with the family; and then have the audacity to ask whether or not you're an asshole for doing so? You are quite lost. Quite lost, indeed.
That being said, if you're looking for some more juicy "Am I The Asshole" drama we recommend you check out a recent post about a bald bridesmaid asking the internet if she was a jerk for not wearing a wig to a particularly unruly bridezilla's wedding.