I say the way his family treats you is not right, even if you do say they love you. Screw em, get drunk before you go, say, "I'll show you pie, M-F's" flash em, then puke on the turkey!!
Oh yeah, I know you won't though.
Look, honey, I am 50, I cook a hundred times better than either of my husband's mothers (that is one ex and one current husband and one mother each, it didn't come out too clear) and I would NOT cook for people who treated me like that. See, love is one of the ingredients and if you ain't feelin' it, it will show. So burn their cake.
Seriously, can you get your mom or a sister or friend who cooks well to help you?