You didn't do anything wrong. Maybe there were better ways of doing it, but the stress you were under--which wasn't your fault, except for perhaps the stress of holding in your feelings--was bound to explode if the problem hadn't resolved itself, which it hadn't.

I'm glad things appear to be getting better. I was in a similar situation many years ago, although I lived in a house, so there was more room. I had a lot of problems. I hope your boyfriend's brother moves out soon, and I also hope he gets off/stays off the drugs.