Found out my boyfriend had a relationship with a transexual a few years ago, should I feel worried?

My boyfriend recently admitted that a few years ago he had a relationship with Thai ladyboy for several months. He also admitted that eventhough the relationship has ended he still called her in Thailand from time to time. He has re-assured me that this was a one of and that I am the woman in his life now, but I still feel worried. I know we live in a society where men more than women are forced to suppress any homosexual feelings they might have, and I guess Im just worried that one day, many years from now he might change his mind, tell me that he has been