I was on chatroulette last night in a mask and ended up having wild ...?

(cont.) with another girl who was also in a mask. We both ended up completely naked (apart from the masks) and went through the whole process until the end when she removed her mask and to my utter disbelief it was my first cousin behind the mask. I kept my mask on and quickly closed the website but I can't stop picturing what happened in my head and it is really playing on my mind. Should I confess to her and just be truthful or do I keep it to myself and let it fester in my mind?