I don't know what happened between you and your mate so I am in no position to tell you anything but I would advice you to ask yourself: Is she worth it? Do I believe her? Can I get over the betrayal? And will I be okay with them dating. If I were you, I would dump both. If they truly loved you they would have never done anything like this. They deserve eachother.
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.