Aita for breaking up with my gf after she threatened me 'because of my sister'

My sister is 22 and I am 29 and my gf is 28, my relationship with my gf has always been great sometimes Rocky yes, we fight but we get back together and I am hoping I'll get back with her this time around as well.

A day before yesterday my sister called me and she said she needs my help urgently I immediately went to her place and I found out she was sitting on floor drunk.

But this time my sister was messy, she had puked on herself and sitting on the floor, I was terrified when I saw her like that, I asked my sister to get up and she tried but she couldn't so I helped her and even with my help she still couldn't walk properly so I carried her

My immediate thought process was that could she have been drugged so I asked her how did she even get back to her apartment and I asked her if she had sex, she said no and she told me she booked a cab

My sister was laying like she's dead maybe that's what alcohol does to a human being, she didn't even care about she had puked herself so I cleaned her and changed her clothes and stayed with her whole night and next day I told my sister that she has to go to counselling or medical treatment and I will help her and she agreed

But when I told my gf next day about what happened she freaked out and she said my relationship with my sister is 'stupid', she said I changed my sister's clothes and I am wrong for doing that and she said she wants to break up with me and I agreed and told her that I am also breaking up with you cause you don't care about me or my family members.