Dear Jax,
Welcome to Susan's. As has been said don't panic. This foray into the world of the Transgendered maybe just curiosity and a desire to understand. You really don't know until you talk to him about it. Personally I believe that if you are in a relationship with someone you must remain true to that person. It is the foundation of any long term relationship. Men are men however and tend to be led around by one thing. It is in their nature. That does not mean that you have to put up with a wandering cad. Confront him with what you have found and ask for answers.
There is a lot of information here at Susan's and we will be happy to talk to you and offer our advice. Just an aside and don't think I'm being critical, just wanted to point this out. Many in the TG community, especially TS's consider the term "->-bleeped-<-" to be derogatory, like wise "trannie". You might want to refrain from such terms. These terms are more often used by the pornography industry. Anyway, fix yourself a cup of tea, or other relaxing beverage, sit down, take your shoes off and set a spell.
Good Journey,
Cassie