Edit: Since someone pointed out that I didn’t post about me maybe being TA I wanted to add on that my mom has constantly been telling me I need to try and form a relationship with my sister and that I need to forgive her for things so to add on AITA for not wanting a relationship with my sister?

So a little background: my (20F) sister (20F) is adopted/married into the family. My mom and her dad have been together since I was very young and my sister and her twin brother’s birth mom has never been involved. When we were about 10 my mom adopted the twins. She has been their mother figure for their entire life and cares deeply for them. But, my sister has always been a little crazy.

Our sophomore year of high school she almost overdosed on sleeping pills but said she had tried to k*ll herself and when the hospital made her go to a psychiatric facility she admitted that she was just trying to get high. Me and my family still haven’t gotten over this but she doesn’t understand at all why we were upset.

Then, the next year she was messaging people online and telling them she was drinking bleach and that she was naked at the park waiting for them. She was sneaking out of the house and once again my mom got her into therapy. They diagnosed her with narcissistic personality disorder and anti-social personality disorder.

The next year, she met a man online and began converting to mormonism. She has told him that our family is abusive and last year she ran away to be with him. We managed to get her back once his family realized she was lying but they kept in contact.

She has gone through therapy and been evaluate by the state and she lies to all of them. Even the psychologists were surprised by how much she lies about for no real reason. When my mom tries to talk to her about it, my sister just says the doctors are lying.

Now onto the situation, the other night she got mad at our little sister and started making up lies and said she was leaving. She accused my mom’s ex of touching her in front of me and our younger sister. She also said that he called her sexy in front of our mom and that our mom did nothing about it.

She has left to be with her grandma but keeps begging to come back but won’t apologize for anything. My mom thinks she should let her come home but my mom is currently pregnant and I don’t think the stress would be good for the baby. So, would she be TA if she cut off all support to my sister?