Should I end my work relationship???

I've worked for the company for almost a year now and I love my job and the people I work with. Being the only female, there has always been a flirty atmosphere with the occasional harmless comment, which I take in good spirit. There has never been any physical attraction between myself and any of my colleagues... until a works night out 3 months ago... ... Id had a bit to drink and was devastated the next morning to wake up in the same bed as my boss! I was in a relationship but ended it straightaway. I had to tell my boyfriend the truth as I felt so guilty. Having worked in offices for most of my working life, I've seen how these things can end and its always the woman that is left worse off, so with this in mind (that and the fact that I couldn't look him in the face), I gave in my notice with every intention of leaving as soon as possible. Luckily he didn't take it too seriously, which I'm quite glad about now as leaving over a one night stand I think would have been a lot worse morally. Eventually we spoke about it and things gradually became less awkward... until it happened again. This time I again got very drunk and the night didn't go too well... at this point he decided he never wanted to see me again in that way. I cant really remember how long he stuck to it for but before long we had somehow got involved in a full blown 'affair'. I'm 27 and he is 30. Before this I had never thought he was my type, but the closer we've got and the more I've got to know him, I find myself more attracted to him than anyone I've ever met.I have really fell for this guy and he says he feels the same. The problem is that he has a girlfriend who he lives with. I have thought about ending it thousands of times and have even told him this, but we cant seem to stay away from each other and if I'm honest I don't want to... I love the guy too much now. He says he isn't happy with her and will leave when he finds a house closer to work but he has been saying this for over a month now and it still hasn't happened. My friends and family tell me he wont do it but I believe him. Its caused arguments between us because I cant handle the fact that he sleeps with another woman every night. Its a difficult situation because its hard for him to spend any time with me and the only time we have is half an hour sometimes after work when we sleep together and then he goes home which makes me feel used and dirty. I hate the situation, his girlfriend has started asking questions and I sometimes start believing people and think he hasn't told her anything (he tells me he has said he doesn't want to be with her) and is just saying it to keep me quiet. Everybody at work and most of my friends and family know and I'm really worried he will tell me he is staying with his girlfriend and I will look stupid and worse of all be heartbroken. I've seen women labelled as the office slag who sleeps with the boss to get promotions or whatever else and I hate to think I am heading for the same situation. I feel bad for his girlfriend but I also cant help who I fall in love with. The situation is getting very stressful and too much for both of us and he has been distant with me lately, should I find another job and cut all ties before things potentially go wrong or stay through the hard times and see what happens???

Louise, you contradict yourself when you state you know the woman always ends up hurt and then turn around and ask what should you do after feeling used and dirty. I'm sorry, but things have gone pear shaped already. You need to realise that alcohol removes the barriers and our inhibitions but that doesn't make it right and alcohol is never an excuse. You have let yourself be used by your boss and in a sense, you have made your bed and now you have to lay in it. If you don't want to, then get out of it and never look back. Learn from this situation, sort your head out and get on with life a little bit wiser.