Hello, just a TW that this post will talk about suicide attempts and toxic behaviors. 

I don't know what to do. Since we were 16 years old, my now 25 years old twin sister has been blaming my mother and I for her suicide attempts and self harm. Both my parents haven't been perfect. They made some serious mistakes while educating us and for a long time were professional invalidators and gaslighters. However, they have made some serious progress since the past 10 years. 

My sister doesn't seem to think the same thing. Even if my dad displayed, in my opinion, behaviours that were wayyy worst than what my mother did to us (for example, my dad used to be always drunk and physically&amp;verbally assault us, meanwhile my mom were more the screaming and slap on the butt kind but only when we did bad things), she thinks my mom is the worst one alive. Well, that's what she tells her friend and anybody willing to listen to her. As her twin sister, I honestly think she does it to get people sympathy and attention. She always been closer to my dad, so that's why she chose my mother to bitch on. When she's at home, she doesn't talk to my mom, but she buy her gifts and help her do chores (without my mom asking her). She even talk positively to me about our mother.  Also, she recently starting thanking her when my mom did nice thing for her. Of course I am not in my sister's mind, but if I really hate someone, I personally won't have these contradictory behaviours.

Two weeks ago, my sister did a suicide attempt. We only knew because her best friend informed us. My parents and I tried talking to her, but she denied her suicide attempt and said that she went to the hospital only to get her anxiety meds fixed. She spent the weekend with us and even went for a fun car ride with me, where we laughed a lot.

On Wednesday, my sister's best friend called us. She was furious and told us that my sister did another suicide attempt. She blamed my mom and I, but when we asked what we did wrong, she hung up on us. This morning, my sister texted me as if nothing happened, sending memes and everything. When I asked if she was okay and told her that I was worried, she left me on read. 

My father called her shortly after that and when he asked what was wrong, she told him that she felt that way because of her "stupid fucking wife" aka our mom and "his other daughter" aka myself.

We tried family therapy when she was 17 and 18 years old, but she refused to hear our POV and left the room each time. Thus, the therapy was unsuccessful.

We don't know what to do anymore. My parents still let her come to their house despite her bitching my mom and never really enforced any rules for her, which I think didn't help.

I am now a social worker and can see that this whole situation is so unhealthy, but I don't know what to do. My family are everything I have, but now this whole situation make me feel so stressed that I consider just cutting all the relationship with them, even if that will probably make me feel super lonely (I do not have a boyfriend at the moment nor any close friends that live near me). I love my mother and father so much, but I can't stand my sister toxic behaviors anymore and since they won't stop talking about it and I feel like I am deeply involved in it while at their home, I think it's the only way to act. I also wonder if I should cut the ties with my twin sister, since she tells everyone that my mother and I are the causes of her distress, but talk to me like I'm her bff and nothing is wrong. 

Did y'all ever had a similar experience or were at my sister's place ? What did you do ? Did that help ? 

I am so clueless. I think my twin sister may be in real distress, but she won't let us help her so honestly I don't know what else I could do there and since it's stressing me so much, I kinda want to put myself first and cut the ties, even if that would make me seem like a real bitch.

TIA