I need advice: Friends with benefits--When should it end?

We all know what it means. The step-down from dating and/or a relationship. Or should I just say booty call?? Most of us have had one, or maybe a few. It sounds practical with a busy life, lots of friends, no strings attached, and the freedom. But when should it end? After a course of time, the woman's heart naturally starts to fall for this person. With the passion, intimate times, its hard. What do you do?? He doesn't want a relationship, but you're crazy about him. I have been in a "casual" relationship for awhile and have found myself completely in love after a year. You don't want to let go of what you have established, yet, its not fair for your self esteem. I have gotten to the point where in conversations I will say, " My boyfriend once....oh I mean, nevermind I meant my friend". Holy crap! I have got a little problem on my hands. The key is to end the relationship of course, harder than you think. I even tried talking to him about taking it a step further, but that wasn't the original deal. So it must be put to an end. It is tough, but can be done. I found out I should have stopped this booty call thing the day I felt emotion. But how is it possible to get over someone who was never yours?? You don't have an excuse for the "breakup". No fights, no cheating, just one little problem, I FELL IN LOVE. Now I find myself hurting because of my decisions. Basically, I broke my own heart. It makes you wonder, was all that "fun sex" for a year worth it? Now I am beginning to believe that booty calls should only last no longer than a couple months. For some emotionally needy women it shouldn't last longer than a couple of weeks. Or maybe not at all. Are booty calls worth it in the first place if we wear our heart on our sleeve? How do you prepare yourself for this situation when just "hooking up" occurs?? You can't control the way you feel, but you must know if you are strong enough to handle it. Thoughts?