I know no child should see their mother in this position

Good day house, please I need your advice. My 8 year old daughter walked in on me sleeping with another man in my matrimonial bed, I did not know she was back from her friend's place. She came in to tell me she fought with her friend and had to leave their place early when she caught another man on top of me. She just stood there looking without saying a word, I had to quickly take her out of the room and told her we were role playing that I was auditioning for a movie role and we were practicing but I am not sure she bought it. What if she tells his father,do you people think she will, this is not a time to judge me, I need advise on how to handle this right now before I loose my mind. I feel like  a terrible mother, I know no child should see their mother in this position. Please I need help