ok, so here's the situation:
my girlfriend and i have been in a relationship since january 2008. everything was great for a long time. we enjoyed each other's company and couldn't get enough of each other. then, we moved in together...after about 6 months of living together, she secretly met up with her ex boyfriend. i only found out about this because i snooped through her email after she stayed logged in one day (i know i shouldn't have from an ethical standpoint). after finding this out, i confronted her, and she told me that he initiated it because he was dealing with problems related to his family and needed someone to talk to. after discussing it with her, i understood as i have been contacted by ex's as well. the difference, however, is that i was honest with her about the contact up front. this created trust issues where i didn't fully know if she was being honest. fast forward to 5 months later, she went on a trip to costa rica with her old college friends and didn't invite me. i understood because everyone needs time to themselves at some point. before the trip, she would occasionally bring up the idea of marriage, and this weighed heavily in my mind. while she was gone, i took the step and bought an engagement ring and various gifts for her return. after she came home, i waited a week or so to make my move. i cooked her our favorite dinner. while dinner was preparing, she seemed distant so i asked her what was wrong. she said that after her trip, she felt confused about being tied down and didn't know if she was ready to be totally committed. so, therefore, i didn't move forward with the engagement proposal. flash forward to 5 months later, and she went on another trip to costa rica with college friends. after her return, things were even worse. we ended up breaking off our relationship because she felt that, throughout her adult life, she had never been alone and wanted space to "find out who she was." well, a few weeks passed with limited communication. then, we had a talk and she said she wanted me to come back, which i immediately drove home to be with her. she was a mess. she kept telling me she was sorry and how she was a horrible person. i told her she wasn't and that she was confused and that it was ok. then, i said is there anything i don't know about, and she went silent. i reiterated the question and she broke down even more and said she cheated on me the first time she went to costa rica. should i take her back? i know that she didn't have contact with this individual the second time since she went to the pacific side on her second trip. what should i do? should i cut her off or give her another chance?