I think i’m officially a horrible person

Thanksgiving break just ended yesterday and I got to be home for five days, my first day back I did nothing. but the second day I spent sitting at home until my brother came to hang out for a few hours which was all good. Thursday was thanksgiving with my sisters family that I don’t know because we have different moms so it was awkward and all. But Friday was my favorite day of break and the reasoning behind why I am a horrible person. Friday I spent the day cleaning the apartment until my sisters boyfriend came home from work where we sat on the couch doing nothing until my sister called telling the both of us to come over to her mothers house. and so we went and were completely uncomfortable being told that we need to get our acts together with our lifetime goals and shit. But it got better after we got back to the house and were sitting around watching tv, my sister fell asleep on the couch so it was just him and I sitting there talking about shit and whatever and when she finally got up and went to bed he and I sat there on the couch talking. like really deep conversations where we shared our life stories and shit with each other. we stayed up all night, he didn’t sleep at all and went to work at 6 and after I left last night I texted him and we kept talking and talking and now i’m here. Feeling like a shitty person because I think i’m falling for my sisters boyfriend. and I have always promised myself that I would never come between them but seeing that they aren’t right together and that he deserves so much better I can’t say anything because I know that I can’t ever be with him, I mean that’s horrible. but I don’t want them to break up because I don’t want to lose him. I love talking to him and joking around, but i’m so confused. it’s not okay to fall for your sisters boyfriend! i’m a horrible person. and i’m beginning to hate myself.