Is AUTHOR wrong in the post ? POST : So I have a family member who is rather manipulative and untrustworthy. I will refer to her as TFM (toxic family member.) 
As an example of her manipulative behavior, when I got married and  TFM’s mother, who is in absolutely no way related to us, wasn’t invited to the wedding, TFM pitched a fit to her father ON my wedding day absolutely REFUSING to come to the wedding unless he picked up his ex wife and brought her with. [the mother is the same way... manipulative, untrustworthy, lies cheats and steals to get her way... that’s another story for another time.]
Anyhow...
Quite recently there was a big show of drama that TFM caused out of jealousy to have something her way and in the process stabbed my whole family in the back, because she refused to report the situation when we found out about it and told her to go to the police, but then turned around after refusing to report it and told the school counselor that the family knew and wouldn’t do anything about it. 
So TFM stabbed my whole family in the back and actually got one person in huge legal trouble over something that was her choice. And it’s not the first time she’s done something like this to get her way. She’s very disrespectful and manipulative and I’ve never had much of a relationship with her due to that and the fact that she’s not that close to me anyway. 
But shortly before the recent drama went down my husband and I had a baby and we’ve been feeling like we aren’t comfortable having TFM around our child. We feel like overall this person is just drama and toxic to us and more especially our baby. 
Here’s where I’m really lost though. 
We’ve been able to just generally avoid contact with TFM and haven’t had conflict yet... but the baby’s birthday is coming up soon and we are going to have to talk to two people in our family who are still really close with TFM that we don’t want her to come to the party (or be involved with the baby.)
Despite coming up with multiple non aggressive, non personal ways to address this with them, these two family members are HUGE on family in a very traditional sense and no matter what we say, we know they’ll be upset. We love them and it’s not personal to them and we REALLY don’t want to upset them, but we’ve talked at great length about the situation and just feel that TFM is... well, toxic.
We’ve even asked multiple other “third party” people who agree that the situation is such that this person needs to be cut out. But I have one very close family member who is telling us that it’s not worth the negative feelings and drama it will cause with the two family members still close to TFM to ask for this person not to come. (Even though the person saying this has told one of those same very sensitive family members something of the same magnitude about another person she cares deeply about...)
So reddit... 
AITA for feeling the need to cut this person out, while potentially risking the feelings of other important family members? 