Ok, so. My mom's side of the family is huge--she has 10 siblings and I've lost track of the number of cousins and second cousins I have. Growing up, some of my cousins and I were much closer to one another than others. In particular, I was very, very close with two of my female cousins. None of us had sisters and we grew up as "sisters" to each other.
Both cousins had children and married in their early twenties. I was a bridesmaid in both weddings. One cousin (let's call her cousin A) and I have remained pretty close--we have lunch regularly and chat. However, the other cousin (cousin B ) is...hm...well, we have gone in different directions, to put it mildly. She has openly insulted both my and cousin A's life choices, has insulted cousin A's parenting choices (for example, cousin B is able to be a stay at home mom due to her family's circumstances, cousin A needed to go back to work after having her second baby and cousin B was very, very mean about it--and on a public forum, for everyone to see), and, additionally, has openly and outwardly expressed her dislike for my fiance.
Cousin A and I have tried to address how cousin B's attitude and actions towards us are hurtful, but she lacks a certain ability to be in touch with reality--she's just trying to be helpful to us, in her mind, and has a right to express her opinion. She continually says that she wants to be close to us and misses us, but every attempted interaction is dominated by her judgement of our lives.
Both cousin A and I have actually started avoiding certain family functions because we don't want to have to interact with cousin B. Neither of us is interested in having a fight, but we're tired of "taking the high road" and just letting her say whatever she wants about us, our careers, and our families.
I am planning to invite all of my mother's siblings to the wedding, but because we are keeping things small, I am not inviting my cousins except for cousin A and her brothers....and....possibly...cousin B.
I feel like I am obligated to invite her to my wedding because I was in her wedding and also because I think that she would be really, really hurt if I didn't invite her. I am already not asking her to be a bridesmaid (I have asked cousin A, realizing that the only reason I had even considered not asking her was because I was worried about hurting cousin B's feelings, but realized that's not fair to cousin A and myself). I cannot, cannot, cannot stomach the idea of having cousin B be a bridesmaid and, honestly, I get a knot in my stomach when I think about how she (and her extremely wild/violent child--he's stabbed people with forks, screams in their ears, etc) will act at the reception (if she even comes, which, of course, since she may be so angry that she's not a bridesmaid, she may not).
I am concerned that her negativity may cause me to feel anxious and not to enjoy my wedding. However, I am concerned that NOT inviting her (much less, not asking her to be a bridesmaid) will alienate her mother and stepfather (with whom I am very close and with whom I have always gotten along well, despite the decline in the relationship with cousin B ). I also have concerns regarding...hm...her use of substances at the wedding.
My fiance would rather not invite her at all, but is leaving the decision up to me.
I know that is very long, but I have been agonizing over this. Any advice on how to tactfully deal with the situation, or what anyone else would do in this position?
Thank you.