I (26M) am very happy with my girlfriend (24F), but her family dynamics concern me. What can I do?
Context:
I met her on hinge 1.5 years ago. Things have been great for the most part since. We have our ups and downs but overall I do see myself wanting to be with her. The only concern I have is her family.
Both of her parents are great people, financially stable, very sweet, very kind people. I'm fairly close with her mom. My gf has a younger brother who is 22, and an older sister who is 27. Both of them are drug addicts, though the little brother is mostly just a weed person. They both have been diagnosed with BPD (I think), though the mom told me she thinks both of her kids are on the spectrum. Currently the little brother lives alone in a studio which the parents pay for, and the older sister lives with her parents at the moment.
The little brother/older sister have a very toxic relationship. We went on a family trip a few months ago to see my girlfriend's family outside the country, and almost every day they would be talking shit to each other, and then smoke weed together. Whatever. Me and my girl couldn't take as many days off, so we got back home earlier, but the parents came home after the siblings. We got asked to pick them up at the airport. I forgot how the argument escalated, but they almost immediately started talking shit. At one point, the older sister started crying and then hitting her head on the passenger seat. I was driving on the highway, left side, and she tried to get out. Thankfully the car is childlocked, but it was traumatic. All of the siblings were chaotic and it was just a lot for me.
My girlfriend told me to not tell her mom what happened. According to her, this happens all the time, and that she just seeks for attention. I told her I'd wait for her parents to come back from vacation, but at some point I will tell her. She told me to tell her mom to tell her she told me not to say anything, which I did. The mom was very calm with me, she was telling me about the struggles, the mental health issues, family dynamic issues, etc. I brought up maybe family therapy, and she said maybe if everyone calms down first, but the way everyone is so hectic and emotional, family therapy would go nowhere. I respected it and that was that.
My girlfriend was pissed at me saying I crossed a line. She said I ruined her night because her mom was mad at her, and her dad was mad at her for "telling" her that. Said I was trying to be like Doctor Phil when all I need to do is just be there for her. I get where she was coming from, but damn the moment the older sis tried getting out of the car while I was driving, I felt involved. It's not like I was telling the mom things that my gf confided in me, this was stuff that was happening to me.
This wasn't the first time I got involved with those siblings. Another time the little brother texted me cursing me out when he was having an episode. My gf and her mom were aware of it, and he did apologize and hasn't messed with me since. My girl said that's just how her little brother is, and that nothing is going to change.
I don't expect things to miraculously change, but I'm not sure what to do, or how I'm expected to handle things, especially when they affect me. My gf is close with her parents, and while my gf tries to put boundaries with her siblings, she cares/loves for them deeply so she'll always be pretty close to them. We celebrate things like Mother's day, Christmas, Thanksgiving, etc. For the most part, those events are ok. I don't want to seem judging on their family, for my parents are split and I have no siblings. Not sure what is normal in these kinds of situations. What can I do?