I have a cousin C (my mom's brother's daughter) who was essentially kidnapped by her mom as a very young baby, so we grew up not knowing her at all. A few years ago, she located us and tried to re-establish a relationship with this side of the family, but she was wary because her mother had poisoned her against her dad and sort of everyone else by association. She and I have grown really close, but she didn't hit it off with any of the rest of our family, partially because of her cautious attitude. Our aunt P is nuts and decided straight off that she didn't like her, has apparently made up her mind that her brother isn't even really C's dad (??) and thus she is an interloper in the family. Oookay.
My cousin ended up with a few family photos that no one else knew of, so she scanned them. Aunt P wanted copies and was really bitter that cousin C had them and she didn't (because she ISN'T EVEN REALLY FAMILY -eyeroll-), so cousin C wanted to send them to her. She didn't have any contact info for aunt P, so she posted them on P's daughter's facebook so she could download them. P went nuclear for C making the photos "public" and attacked ME for no other reason than I am close with C. (Screaming at me "You tell that bitch blah blah" at my sister's baby shower. Classy.) She has since apologized for taking it out on me for no reason, but not for being totally unreasonable in the first place and she still hates C.
Currently: I'm planning a small family party for my new baby and cousin C is most definitely invited. I seriously doubt aunt P's ability to "play nice" as she's notorious for holding grudges. My mom thinks I should invite aunt P and not cousin C basically because "C will understand and P will go nuts with anger at not being invited" but I think that's crap. I know that P will try to turn everyone in the family against me and never let it die if I don't invite her. WWYD? I'm sort of tempted to invite her but make it really really clear that C is coming, I love C and will not tolerate rudeness against her in my house, and just hope that P will choose not to come of her own accord. I don't want to make C uncomfortable (since IMO she has done nothing wrong), but I also don't want to cause an absurd family war by deliberately not inviting P. Thoughts?
(Yes, my family is all batshit crazy - just trying to get by and not piss anyone off too badly.)