What to Do Now? Mother Confirmed Fear I Was Never Prioritized

Without going into all of the details, I was a parentified child who had to look after my siblings and mother. Mother never acknowledged the toll this took on me and was often emotionally unavailable. I've tried to talk to her before about not feeling supported but was "punished" for it and met with the silent treatment. No resolution; I just had to try harder to make her not mad at me until she would talk to me again (finally broke that cycle and now just wait for her to be done ignoring me).

On Christmas, my sister got mad at me (pattern is sister explodes over the slightest thing and even when I haven't done anything wrong, my mom tells me I'm always the one that needs to be the bigger person, apologize, just let it go, etc.) Not once has my sister ever been asked to apologize for her verbal abuse, and now that I'm learning to set healthy boundaries and stand up for myself and trying it in these situations, my mom just tells me to drop it and leave my sister alone as if I'm the one starting the conflict and not simply saying it isn't okay to be yelled at over stupid things and she can state her issues in a calm way (ex: I didn't take my shoes off immediately after entering the house, used the "wrong" bathroom because now that I don't live at home I'm supposed to use the one reserved just for guests, etc.) There's more examples not related to the home, and essentially my sister thinks very selfishly and needs to be able to micromanage and control everyone's actions and my mother just let's her.

So of course in this latest instance, my mom says, "well just tell her you're sorry to smooth things over." And I got so upset and all the years of having my feelings invalidated came crashing down and I started sobbing. My mom continued prepping the turkey as if nothing was wrong. My husband stepped in and said "do you want me to take over prepping the turkey so you two can talk?" And my mom said "oh no, I'm almost done." So my husband pressed again, "I think OP wants to talk to you." I finally got the courage to say, "Why is it so important for me to always have to consider sister's feelings when I've done something 'wrong' but she gets to scream at all of us for no reason and you never intervene because 'that's just how she is'"? And my mom said, "because she's more emotionally disturbed than you." I pushed back saying "but don't you think I deserve some support too? It's so important for me to pretend I'm not bothered and have it all together all the time, because if I don't, I get NOTHING. I'm standing in front of you sobbing, and you're just prepping the turkey like nothing is wrong. " And my mom said that she does support me and take my side. I asked for an example. She said that whenever my sister and her come are invited over to my house for dinner (which is maybe a handful of times a year as husband and I usually come to them), on the drive over she has to remind sister not to say anything to upset me, as if coming to my house is some huge sacrifice they both have to make and that reminding her "not to saying anything that would be upsetting" is the same or even comparable to my sister needing to apologize for the way she treats me or her needing to be the one to "smooth things over" in a conflict.

So in that moment, I had my answer: no matter what, I will never be supported or have my feelings validated in any sort of conflict or disagreement. I get that as adults, my mother doesn't need to intervene and I don't even want that--but she prevents me from defending myself and acts like I'm the one causing issues if I try to.

I left to get some space, saying I'd return for Christmas dinner and my sister messaged me saying it was such a cruel thing for me to leave my mother on Christmas day, and I sobbed for an hour in my husband's arms. When my husband and I returned for dinner, I was met with the silent treatment and my mother ignored me the whole time.

Now my question is, where do I go from here? If I'm no longer bending over backwards to make sure my family isn't mad at me or I'm always doing the right thing, what can I do to fix this? What kind of relationship can I have with my family?