Toxic Family: Should i just elope?

Tia

I have a dilemma. My fiancé and I have finally started planning our wedding of next year. The problem is that my family is extremely toxic, so much so that I only want one of my two sisters to be in my bridal party. The other one has tried to break me and my fiancé up out of pure jealousy. She constantly bad mouths me to him when I'm not around and encourages him to leave me. She does the same to me about him when he's not around. She's very unstable and mentally ill. I'm pretty sure she's got hardcore narcissistic personality disorder. Much like my mother.

Well my nicer sister feels like she won't get to be a bridesmaid if my other sister can't bc she'll make a big deal about it. Which is very much her M.O. but me and my partner are adamant that we don't want someone standing behind us who doesn't support us. If I don't make her a bm my Nana who's very small-town minded will spend all of my wedding guilt tripping me about "family" and my mother will go around telling people that I'm a monster for my decision. She's usually going around spreading lies about me to her side of the family to make me look bad and then picking fights with me to leave me feeling emotionally violated and then playing victim when I stand up for myself. She's extremely toxic so I usually keep her blocked.

Just yesterday she asked when she could see my daughter(her first and only grandchild) for the weekend. My daughter is 7 months and even tho she's now on purees and cereal she's breastfed and I never had a surplus of milk so she can't spend more than four hours away from me and that's if I have milk pumped which I usually don't since my electric pump broke. And even if I did 7 months is too young for overnight and my own mother starved and abused me as a child, she's not spending any time alone with her.

Well she expected me to meet her in another state and hand off my child for the weekend. I said no and told her my daughter basically needs to eat ya know and she responded as if I had a choice not to feed my child and feigned as if her feelings were hurt. Mind you, nothing is stopping her from driving the 6 hours and staying for a couple days to see us. We can't afford a road trip since we're planning a wedding and a move cross country in a few months.

Anyway, point is my mother and sister are absolutely toxic and I don't want to feel like shit on my wedding day so much so that we've been talking about eloping even tho I really want the whole shebang. I don't know what to do. Do I make my psychotic sister a bridesmaid knowing that I run the risk of her actively trying to prevent my marriage or do I not include her only pissing her off and giving her and my mother ammo to use and gain up on me? Or should I even bother with a wedding if my mother is just going to emotionally abuse and insult me every time she needs to feel better about herself?

Still having to take her abuse at 24 has really destroyed me psychologically and emotionally and it would kill me to have to feel that way on the day of my wedding. It's gotten so bad that my fiancé has been pushing me to go to therapy bc every encounter with my mother leaves me suicidal and insecure.

And for those who think they're capable of behaving for one special day...my aunt got married in November. My mother was a bridesmaid. She walked down the aisle with this "whatever it won't work" face and took off her dress before they did bridal party photos. She walked around at the reception in flannel and jeans. My sister got so drunk she argued with any and everyone. I just don't know if I'll ever get to have a special day.