Mother fucking with her son’s two friends

I couldn’t stand it anymore. I was fed up with walking past my sister-in-law’s room (because I live with my brother) and seeing her asleep in her underwear. She often got drunk and went to bed in her underwear, but she also did it sober, so it was obvious she was sending me signals. The other day my brother was working nights, and again my sister-in-law had a few drinks, went to bed, and left her bedroom door open. I had no choice but to go in and do what I should have done a long time ago.