My sisters boyfriend is GAY

Okay so my lil sister recently broke up with her boyfriend of a few years who was a nice guy never drank or did drugs helped her a lot to get her health issues in check he's a vegan and she has stomach issues that got so much better he would cook for her everyday. she said he had no drive to better him self financially do she broke it off, I understand her decision BUT she rebounded with this new guy who is totally out of work lives with his parents and to make matters even worse is a recovering heroine addict I can't help but be worried how does she think she did any better ? And now she decided to not be vegan anymore because he's not and is constantly complaining to me about her stomach issues. I just don't like this new guy, he gives me the creeps and she also told me he's hooked up with guys in the past but he claims he's not gay 🙄🙄🙄 he actually tried to touch our guy cousin in a inappropriate way and he nearly beat his ass. I just don't know what is wrong with her. She also has changed her style completely to accommodate him. Even more disturbing is she's an artist and I've seen some very disturbing artwork of him by her on Instagram naked in gay sexual positions showing off his ass or dressed in her underwear and her wearing a dildo 😖😖😖 I know for a fact these are drawn from real life and it just makes me sick to my stomach. She tries to come visit me and my 1 year old son and has tried to bring him but I'm really not comfortable with a stranger in my home I mean she just met this weirdo and I don't know how to tell her he's really not welcome and that he makes me uncomfortable. I just hope this doesn't get serious