Thank you all for your replies! In response to some of the questions, the prostitute was a she-male. He did not cheat on me as this happened before we met. He says he has never been unfaithful to me. Our sex life is great. He has always been an incredibly attentive lover and we both are very open to experimentation, however I never expected this and am all the more shocked. He is, however, very fascinated with anal sex and that's something that I haven't been able to give him (just find it hurts too much). I have indulged other fetishes and he has certainly indulged my fantasies. I thought that this might be a better form of therapy for myself because I would be talking to people that may be actually living/experiencing or can relate to some of these issues more so than a therapist.
He won't go to therapy himself as he insists he is not attracted to men, will give up the porn surfing and only wants to be true to our marraige. I would obviously be very hurt if I found out that he was gay/bisexual. I think the saddest thing for me would be the fact that we were living a lie more so than what his sexual orientation would be. Life should not be wasted being something that you are not.
I would be happy to indulge him (ahem) but who is he thinking of? Me or a man?