OK so long story (sort of) short, my stepmom flipped out on my sister for talking to my father's ex-girlfriend (which was someone important in my sister's life when she was growing up). My stepmom is VERY wrong in this situation but she doesn't think so even after my dad told her otherwise. My sister and her have not talked in over a year and the holidays have been really tough cuz my "parents" invite me over but never my sister. I've always told them that I had plans with my sister.

SIDE NOTE: My dad and sister see each other when the 3 of us go out once every other month or so. & My sister just went through a divorce a few months ago so her circumstances have changed.

Well my grandfather told my sister that my dad is have a 4th of July party tomorrow. My sister is going to crash the party. She asked me for support and an escort to the party. I am very stoked she is going...

BUT My stepmom is going to be so angry and she is going to assume it was me who invited my sister. I told my sister I'd take the fall but I am not ready to take the wrath of my stepmom. She is psycho! (Non of my dad's family like her anymore... she has flipped out on all of us at one point for things she is so wrong about)...

Any ideas how to handle this? I am just as anxious/nervous as my sister who is crashing this party. eep!