My (28M) sister (25F) has come to me asking for advice on multiple occasions regarding a guy in her life who is extremely toxic. Treats her like she’s temporary and disposable, gave her a lifelong STD, keeps her around when convenient. She can’t kick her obsession with him. She also slept with his brother, the other “good influence” she talks about to my parents. In a recent conversation I had with my mom she mentioned something about “oh thank god your sister has those 2 friends who are great influences for her…they seem like gentleman that she can count on in life.” Me, being the caring and concerned older brother I am, told my mom that those boys may be the 2 people that have caused her the most damage in her life thus far. My mom was shocked. I gave no further details. My mom doesn’t even know she is romantically involved with them. The one brother has no idea that she slept with the other out of spite. She’s in a very plateaued phase in her life. We live together and she always lying to me about where she is, what her future plans are in life… I asked her to watch my dog while I was gone for a weekend and as soon as I left she brought another guy over (not one of the 2 I mentioned) and my dog, being a reactive puppy, freaked tf out. Before I left I told her that it is very important to me that my dog is well taken care of, which is why I was paying her. I told her to walk him daily… she didn’t walk him at all, poor little guy only poops on walks. Smh she even turned off the Wyze camera I set up to monitor my puppy as soon as I left. She didn’t think to turn off the second Wyze camera I had which is how I knew what was going on. Either way I showed her patience and didn’t even get on her about the ridiculous decisions she’s making sleeping around. I finally moved out yesterday and on my way out we got into a discussion in which I basically blew up on her for being a selfish sister and only worrying about herself and her fun times. I told her that her priorities were all messed up. I also told her that I told our mom about her2 “friends” she always talks about and how they aren’t good for her. I think I reached a point where I was tired of being lied to by the person I cherish most in my life. AITAH?