What to do?!!!

First of all I would like to say that I would appreciate any advice regarding a problem I have...Although I know that I have to resolve it myself, somehow. I am in a rather long relationship, for about 7 years, Ive been living with my boyfriend for the past four years, we even own an apartment. He is an amazing guy and we have been through so much together. He is the sort of person you can always rely on, no matter what . Just amazing...Still, 2,5 years ago I met another guy, we started having an affair and it has been going on ever since. I cant stop thinking about him, love spending time with him, the sex is just amazing. I think Ive never had such a great time with a guy, we are so much alike. The problem is that he lives in another country so I don't get to see him as much as I'd want to. Again, I think about him constantly, even when Im with my boyfriend, which is horrible. I even tried breaking up with my boyfriend, but in the end didnt go through with it because just the thought of leaving him was too painful. When it comes to sex, I think I am no longer attracted to my boyfriend, and, on the other hand, love having sex with my lover. Now Im thinking again about leaving him but it seems too complicated. Also he thinks that everything is fine because Im trying very hard not to let him know that I have fallen for another guy, so I wouldnt even know what reason to mention when breaking up. I mean, other than "honey, Ive been cheating on you for almost the past 3 years"...Help!!!!