Worst lunch break ever

"Some years ago, I was sharing a house with my girlfriend and another female roommate. I decided to go home for lunch, which was out of the ordinary for me. Got home, and could hear sex from the roommates room. Tiptoed back to the kitchen, fixed a sandwich, cut it in half, and my roommate walked in the front door. We look at each other and a sad, sad frown overtakes her face. Sandwich still in hand, I walk into the roommate's bedroom, and my girlfriend is straddling some guy. They are both frozen with fear. I throw the sandwich halves at my ex, both hitting her square in the face. She runs over and starts hitting me. The guy escapes through a window - he was wearing only a t-shirt. After about 10 minutes listening to her sob and blame everything on me, we hear sirens. Apparently, a man with no pants had pulled out into fast moving traffic and caused a huge accident."