In laws causing problems.

I have always had problems with my husbands one sister. Shes just a very aggressive person and she lashes out at absolutely everyone all the time.. this Is something that their whole family has just "accepted" (they let her get away with her great big adult sized tantrums)

I have been through many phases of trying to cope with this, I went without speaking to her at one point, and I have also just let her walk all over me at times because i didn't want problems. She seems to attack me (verbally) quite a bit more since I had my son. She knows this will cause problems with my husband and I, how could it not when his whole family takes her side. The last thing i want Is for there to be tension with him and his family but I have really tried hard lately to get along with her, and for the past few weeks things seemed to go well. I'm now pregnant with my second baby. Anyway last night she stepped way over the line, my son was an hour past his bed time when we were at the grandparents house, and he threw a massive tantrum because he was upset we had to go inside and get ready to leave. Anyway, the sister comes over and tried to grab him from me when i was comforting him, I held on to him for a second and looked at her and said " no, dont take him I got it" she just jerked him out of my hands, and walked away.

I was honestly so angry, but obviously because shes so explosive I decided to just tell my husband to get our son ready and we needed to go.

His sister came to me at the door as I was getting my shoes on and said " I just thought I was helping"

I was feeling so overwhelmed and all I could really manage to say " I understand that, but I said no. And you took him anyway. And I said no, and it upset me." I didn't even raise my voice I just wanted to go home.

Anyway she completely exploded started calling me a cunt and she started crying and freaking out. She is telling everyone I yelled at her like she was a toddler, even though literally everyone was in the house and knows I didn't raise my voice. But of course his other sister chased me out of the house to yell at me. While I was getting my son buckled in, and at this point I did raise my voice and said I wasn't going to sit there and be attacked again when I didn't do anything wrong. And then I said goodbye. And we left.

I'm just feeling so emotionally drained today. I am sad and feeling defeated. I cant keep doing this with his family and I just dont know how to deal with this anymore. Everyone expects me to apologize because "she did nothing wrong" and I have always had to be the one to forgive and forget and pretend nothing happened. I dont think I can keep doing this with her. I dont know how to move forward with his family after this, my initial response is I dont want anything to do with them, i have given all I have to try and keep a relationship with them and it always backfires. But I dont want my husband to lose his family.. I just need words of encouragement or advice. How do I keep things smooth without being a complete pushover? Sorry for long post, and thank you for bearing with me! Any advice is very much appreciated. 💞

UPDATE: I took a whole day to think about the situation. I have decided that outside of family events she will not see us. I think this is what's best for our family, and my husband is on board and understands. I had to explain how impressionable our boy is and the way that her and her husband act around him will affect him in the long run. And that we need to do our best to protect him from toxic people. This is the first time my husband has stood by me and defended me to his family, so I am very happy about this. But we really seem to be on the same page, especially when it comes to our son. I know he wont talk to his sister about the specific situation, but he has told her what our new boundaries are. I think I can say I am content with the decisions made. Thank you for all your wonderful support! XO