I've been NC with my mom since December of 2021. I have almost zero contact with anyone on that side of my family (uncles, aunts-- my father has passed). It's not difficult, since I live in another country halfway across the world. My father was an abusive alcoholic-- my mother is an emotionally immature adult who uses the silent treatment, is passive aggressive, and always makes everything about her. She also often belittles my feelings (I'm "too sensitive") and refuses to talk about anything she doesn't like, calling me "verbally abusive" if I try to bring up something I want to discuss.

However, I am close with my younger sister, and our relationship is precious to me. She is getting married in August and I am flying, with my husband (who no one in my family has met, since we live abroad and had a super small wedding during covid when the borders were closed) to the US to attend her wedding.

I have not been back in the US in 10 years and that alone makes me nervous, but mostly, I have no idea what to expect at the wedding with my mother. She loves to play the victim and tells all kinds of untrue stories about me to the family. I've tried to mend the relationship many times, but she still holds these weird grudges against me and badmouths me to the rest of the family. She plays weird games that remind me of a high-schooler, like blocking me from seeing certain posts on Facebook, but allowing others when she wants to make a point.

I have no idea how to behave when I see her, and I am sure I will have to see her, at the very least, for photos and such. I have already spoken to my sister and one auntie I am close with to make sure our seating is separate (my sister totally understands my issues with our Mom, she's just more conflict avoidant than I am), but I am feeling extremely anxious about this trip. I guess I plan to just be cordial, like I would to any stranger? But she's not a stranger. Do I just smile and avoid having to interact with her as much as possible? I can't not attend my sister's wedding-- this means the world to her, and I have a few administrative tasks I need to get done while back in the US, but most of all, I want to be there for her. I have not been home in so long or been part of any other family functions, but as she is the only blood family left in my life, I want to be there on her big day.

Any tips or advice on how to avoid any conflict while maintaining poise and grace?