gf gets fucked by black cock

My gf had her first black cock experience last weekend. Since then she hasn’t stop thinking about it. On Mondays, she doesn’t work. I get home, and from my across the street I can hear screams and moans yelling "fuck me! Make me your black cock whore!" I thought my gf was watching porn. I opened the door and saw that she was being fucked. I get so aroused, I try to join in but she tells me she only take bbc from now on but I can clean her up and eat her pussy. I managed to get a few pics.