My stepmom insults my dad about my looks and later on, she brings home another man after a celebration

The other day my girlfriend and I went to a celebration, where she drank a lot. When we got home, my stepmother started insulting me about my appearance, saying that I was not as attractive as her boyfriend. I tried to defend myself, but she kept going. Suddenly, a man came in whom she brought from the celebration. She started flirting with him right in front of me, and it seemed that she was going to fuck him right there.At that moment, my dad came in and saw this disgusting spectacle. He started yelling at his wife, and the guy quickly ran away. Dad took me into the other room and started talking to me. It turned out that my stepmother had been doing this for a long time and that she was fucking different men. This was a real shock for me, and I did not know what to do.