How do I break up with her and still she her sister?
So, I know I am going to sound like a huge loser, but here it goes. Started seeing this girl (R)not long ago, and it had been going all right, but one night I ran into her older sister (C) at her work-they both work at the same place. We went out for drinks and one thing led to another and I drove her home and we did it in my car. She also has a man. It happened a few more times-my gf's sister is way more sexy hot. The thing is is she wants to keep hanging and not tell her boyfriend. But, I just can't be that way. I feel bad whenever (R) and I go out-she is a nice girl but just doesn't do it for me. I told her sister I had to come clean and then we could take it from there, but she says she will deny it. She lies to her sister all the time, about dumb stuff. So, do I just break it off with (R) or tell her what is going on?