How can i explain to my girlfriend that it's not my fault but the masseur's fault?

Nothing like this had ever happened to me, much less with my girlfriend at home. i hire a masseur at home because my neck has been fatal for a few days. how wonderful when i lie down on the table and he begins to massage me. suddenly i notice how he reaches into my pants and i can't resist. things get complicated and we end up fucking my girlfriend in the kitchen ...