AITA: Someone i was good friends with and helped her improve her drinking and hooking up habits literally hooks up wasted in front of me. Am i the asshole for angrily texting her about her actions?
 Full story below:
I became good friends with this girl via a mutual friend. We became close and I was sort of an older brother/mentor for her. I helped her through her past traumas and was attemtping to help her focus more on school than on partying drinking and hooking up. 
This halloween I went to the bars and saw her. She came in drunk with a friend. I was like ok so she has someone supervising her, thats good. Except the friend turned out to be drunk too and kept feeding her drinks. 
They saw me and we chatted some. I took their pictures for Halloween. We then headed to the dance floor. The friend im mentoring, in no more than 5 seconds, found a guy and was kissing him on the dance floor. I finished my drink and just walked out. I then sent her quite an angry text in a mixture of scolding and yelling at her. 

So am i the bad guy in this?