Yes I was with a women for 5 years and around year four things had degraded to the point where we were basically just living in the same house. Now don't get me wrong at the time I still loved her but she had fallen out of love with me and it was clear by her actions, how she spoke to me, treated me, and that we hadn't had sex in a year or more..

Anyway, like you OP there was a women I worked with who I fell for. It started out as casual talking, friendship, then flirting and eventually I realized I was developing serious feelings for her. I tried to push it to the back of my mind but the worse things got at home the better the escape of work and my infatuation became.

There was a point at which the women from my work made it very clear that she wanted to be with me physically, and I had to decide what to do from there should I leave my girlfriend, should I cheat, or should I break things off with my coworker before I do something that could hurt the people I cared about? I choose to stay with my girlfriend, I had to quit my job because being around the other women I also had feelings for was to difficult.

Fast forward a few more months and things with the girlfriend have gotten to the breaking point and we break up. I find out the weekend of our fifth anniversary that she had been seeing someone else for months and had also cheated. I felt broken and betrayed and moved back home with my parents for a while.

I wonder how things would have turned out if I had made one of the other choices. Would I still be with my coworker? Would I have have felt better to have been the cheater instead of the cheated on? I don't know. But, if things didn't happened how they did I never would have met the women I married and love more than I though tit possible to love someone. I guess what I'm saying is that there are no easy answers when it comes to love and you should do what you think is right.