Leaving a friend out of your bridal party

So for backstory I have this friend from college and we all shared a friend group. A few years ago she started trying to spread a rumor about one of our mutual friends and had a full on meltdown on a group trip after we called her out for lying which effectively ended her friendship with everyone in the group except for me. She is dating one of my fiancés college friends so it was harder for me to cut her off. Since this disaster of a trip she has on more than one occasion said nasty things about my friends (her former friends) to my face which has made me incredibly uncomfortable. I’ve had to keep my friendship with her completely separate because my friends want nothing to do with her. A lot of our conversations involve telling me information about other people that I am not friends with or complaining and negatively and I always leave my time with her feeling stressed, anxious and a little gross if she’s pulled me into her negative conversations. Cut to today—I am now engaged and she had fully assumed she was in the wedding. She even told me she would end our friendship if she wasn’t in the bridal party. My fiancé doesn’t care for her so he hadn’t invited her to the surprise engagement party. She was blowing up our mutual friends phone all night (probably talking badly about me). I have been so anxious about telling her she can’t be in the bridal party because it would just be an absolute disaster and create so much drama and stress for me. I didn’t want to tell her it’s because everyone is not wanting her around so I chose to tell her a half truth which is that I needed to prioritize family and those who already had me in their wedding because we have to keep the numbers small. She seemed fine and said it’s your wedding do whatever you want etc... Now I find out months after that conversation that she has messaged that same friend (who she doesn’t know is a bridesmaid) that she got my save the date and that I have been irritating her all year long about coming in on a Thursday (which I have never said and we have barely talked all year) and that I so rudely told her she’s not a priority in the wedding. Which isn’t how I phrased it and I told her in the kindest way possible and that I was struggling not to hurt anyone’s feelings. Basically I want to uninvite her because if she’s speaking this way now what is she going to say at the wedding? I completely understand that she’s most likely hurt over all of this but she really left me no choice after the way she acted towards the rest of my bridal party. I’d appreciate any advice on how to handle this situation. I don’t want to make things weird for my fiancé who is friends with her boyfriend...