First of all, I want to say that English is not my first language, so if something sounds off, I’m happy to clarify.

My sister (31), who is my half-sister (we share the same mother), is getting married this May—but neither my mom nor I are going to the wedding. Here’s the context:

She left our house at 15 to live with her father, and since then, she changed a lot. I believe this is because she was raised in a household with toxic people. Her father cheated on my mom, married his mistress (now her stepmom), and had another child with her. Naturally, her father and stepmom prioritized the new child and neglected my sister. My mom had to step in many times, but my sister was always desperate to be accepted by that side of her family, which made things complicated. She never set boundaries with them, especially with her stepmom.

As the years went by, she clearly favored that side of the family and gradually distanced herself from us. She became someone who only seems to care about appearances and only reaches out to my mom or me when she needs money—something very much in line with her father’s personality. Another issue is that I’ve been struggling with depression and anxiety since 2018, and she’s always dismissed mental health problems as fake, saying that people just need more “willpower” to get over it. Because of all this, the relationship between her, my mom, and me has become strained.

Even though things aren’t the same, we’ve always tried to maintain the relationship—for the sake of family. But it’s hard when she constantly acts indifferent and makes passive-aggressive comments. A few weeks ago, we received her wedding guest list and saw that she decided to invite her stepmom—despite having told us earlier this year that she wouldn’t. Because of this, my mom declined the invitation. She explained that she wasn’t comfortable attending since the stepmom is the woman her ex-husband cheated on her with, and she’s always made hurtful, passive-aggressive remarks, trying to steal attention whenever my mom was around.

My mom has never fully healed from that trauma. We’ve made a lot of concessions over the years for my sister’s sake, but this was where my mom drew the line. Since my sister still chose to invite her stepmom, my mom won’t be going—and honestly, I don’t want to go either. I don’t feel comfortable being at such an important family event where my mom isn’t considered, especially since she always dreamed of seeing my sister get married.

So… what do you think? AITA for not going?