The husband writing this (not the wife this time). Dude we all make mistakes in life and really you know how things are in the UK, many have casual and don't know each others full names for a start. She has not cheated on you that was all in the past and give her the benifit of the doubt, she has been honest with you. Also if she had no complications or commitments at the time what is the problem with having a bit of nookie!