“he thought i was my mom”

When I was 16 I got home from work and was watching tv on the couch and fell asleep. I woke up to me facing the couch so it’s all I saw and I felt someone laying behind me and rubbing me and touching me. I don’t know why I didn’t do anything but I just froze and didn’t know what was going on since I had just been asleep. Finally I moved to turn over but he got up really quick and went to my moms room. It was my moms boyfriend of five years and I heard him tell my mom what happened and he said “I thought it was you” and my mom just laughed. I’ve never brought it up to her because she just laughed when he said it. I panicked in the moment and just didn’t want to think about it. I’m 20 now and I still feel like shit about it because I feel grossed out about the whole situation. Does anyone have any advice to get over this?