Am I a bad person for this...?

I am 17. I have a girlfriend although I also have a little sister. I have always been somewhat sexually attracted to her. She is about 5 years younger than me. I always watch her when she is sleeping, I tend to get hard and I begin jerking off to her. Whenever me and my girlfriend I tend to think of my little sister. One time when we were having s** I accidentally called out my little sister's name.. It was awkward. One day my sister walked in on me jerking off. She came in and asked me if I needed help, I was a little embarrassed but I nodded gently. She then put her hands around my d*** and begin moving them up and down. It felt good... She then used her mouth and gave me a b*******. Eventually I came into her mouth. She swallowed all my c** and smiled. She asked me if it felt good. I told her that it did and she got up and pulled down her pants and asked me if I could "play" with her. I went ahead and begin rubbing her p****. I pushed my fingers inside and moved them back and forth. After every few minutes I pushed one more finger in, eventually 3 fingers were inside of my little sister's p****. Eventually I pulled all three of them out all at once, my sister gave out a loud moan. I became hard again and she noticed, she asked me if I wanted to take her virginity. I said yes, desperate to put my hard d*** inside. My sister lying down on the bed on her back she spreads her legs out, leaving an opening for me to insert my d***. I push my d*** inside of her slowly going deeper and deeper. Eventually penetrating her tight p****. She wrapped her legs around me, accepting my d*** inside of her tight p****. He go on for about and hour or so... Eventually I c** inside to her. After finishing up, I pulled my d*** out of her and looked at her. She looked exhausted and tired, I decided to cuddle up next to her and sleep in bed with her. My girlfriend was watching the whole time... me, her, and my little sister ended up having a threesome the next day.