I have found out that my bf has been cheating the whole time we have been dating with his ex. He has told me he loves me and has proposed. The ex has written several letters to him telling him how she loves him and how she cant believe that he is marrying me. The letters tell different dates and specifies when they were together. I think she did that so that I would find about her. He told me he was confused and now he has made his choice to be with me. I am scared that he will cheat when we get married, since he did a lot. It has only been 3 months that he has not seen her. Should I be concerned?