My friend (16M) is dating my sister (15F) but I don’t want to be associated with him anymore because of what he did to another girl at school. How should I do this?

My friends been dating my sister for a few months. He asked me if it was okay with me that he asked her out and I said it was fine, I honestly didn’t care at that moment. I’ve seen him get food out of our fridge, as he was staying at our house for a week, but my parents told me not to get mad. He refused to clean up after himself, I have to clean up after him whenever he comes over. <br><br>But the line was crossed this week. One of my classmates (15F) posted about what my friend did to her while they were dating. It came out that he was cheating on her with multiple girls and lied about it. He was gaslighting her and making it seem like everything that happened was her fault. I know that he’s been doing this for a while. <br><br>I’m fed up with him, and I don’t want anything to do with him. When he comes to my house, I go out and do stuff, and don’t come back until after he’s left. I’m going to be more open about him, and let my friends know that I don’t want to be associated with him, because he’s a piece of trash. I’m probably gonna be called a rat for this, but he’s asked me to do weird stuff for him. I can’t do anything about it now because he’s not my friend. <br><br>My parents told me to just stay out of it because he’s my sisters boyfriend. My dad even said that my sister needs to grow up and see that he’s not good for her, but my parents don’t want to intervene. I just don’t want to be around him.