Would it really be the end if you explained everything to her and said it wouldn't happen again? My fiance has said he wouldn't dump me even if I cheated on him (which I have no intention of doing) because he loves me too much. I don't know what your relationship is like but if she really loves you she'll give you a second chance. What you should be asking yourself though, is if you really love her. If you do, how could you cheat on her for so long? It's not like it was a one off spur of the moment thing.