<human>: My boyfriend and I have been together for over 2 years. He's still friends with an ex that he was in one of those 'on again, off gain, constantly fighting, not really healthy' relationships with. I don't really like it, but I put up with it, because they barely interact. I trust him, but I don't trust her, she strikes me as super manipulative and just makes me uncomfortable. 

We went dancing with her and another friend last fall, and unbeknownst to us she was dropping acid, and ended up so ed up we had to bring her back to our place and let her sleep on our couch. I don't do drugs, and I think people who drink to much to be able to drive are incredibly irresponsible. I was livid that she did that and I had to let her sleep in my house and told him so, and he said that was understandable and wouldn't happen again. 

Tonight he comes home and "Hey [Ex] asked me to go to karaoke with her, so we're going to go tonight at nine!"

Not cleared with me. I hate karaoke. I don't want to go. But now I feel like I have to go, and chaperone this shady bitch, and I have no doubt she's going to do something to make her our responsibility again, because that's just the kind of person she is. 

I'm livid.

Can you summarize the given text in a few sentences?
<bot>: I don't want to hang out with his ex, but nor do I want to come off as a jealous nazi she-beast. What do?