May somebody please help me, I'm feel like giving up on life?

It all started when last Friday I mistakenly made love to my sister because I mistaked her for my blowup doll also known as Nina. Well ever since then she has been returning the favor by giving me fellatio and giving me s. To make matters worse, yesterday I accidentally d in my mom's mouth and today, she walked in on me while I was masturbating and basically milked me. The problem is that Nina lives in the house with us and I don't want her to find out. My sister comes in my room to blow me sometimes while Nina is in bed with me, but she's a deep sleeper. How do I stop Nina from finding out about my cheating ways, i love her very much and i don't wanna break up...PLEASE HELP?