Ok so I am new here and I come seeking advice and don't care for rudeness... This is my story. My ex and I were together for 4.5 years. From the start of our relationship it was required that I must have a friendship with her younger sister/bestfriend. No big deal. Well on that four years her sister and I became best friends and nothing more. We hung out a lot even when my ex wasn't around. To sum up that part my ex and I have a 2 year old son and things were not working out no matter how hard I tried. She had the need to text and flirt with random guys she met at work and I'm sorry but that's unacceptable. I left her 6 months ago and e are very civil with one another. This is where it gets messy! Her sister and I remained best friends and we still hang out.( ex is fine with it) About a month ago her and I were drinking and one thing led to another and we ended up sleeping together. We both afterwards agreed that it was wrong and we can't let that happen again... Needless to say it has continued almost everyday for the past month. My ex has no knowledge of this going on, but she is going to find out if we continue. I didn't do this to be a slime ball, I'm not a pig of anything like that. There was a major connection when we kissed. We know everything about one another and we are ok with our pasts... What do I do? This was never planned but it feels way to right to be wrong and we both agree. It's a very messed up situation, I know. But I think because we were so close for so long it was destined to happen. I'm not worried about how my ex thinks of me or anything. I worry about her sister!