So telling the truth means being exposed to pain? And that telling me the truth would break down this relationship he created with me? It sounds like maybe its embarrassing that he has these weaknesses or insecurities because he knows its messed up?
Quite astute, yes. He had no control over his real life, so lying makes a life that he controls, where he is safe. Anything that breaks through that shell will be extremely alarming and strongly resisted; once the pain starts, who knows where it will stop.
And absolutely, his relationship with you is something he lied his way into, lies to sustain, and in his mind depends on lies to work, because he perceives the truth as something that makes him abnormal and would deny him a normal relationship; the truth is so vile, people would flee vomiting.
(Note: it is not normal for him to attempt to cheat behind your back and lie to your face when caught. I am merely using what I strongly suspect his definitions to be, but you are an equal partner in the relationship and deserve to be respected and empowered.)
I'm still grasping the whole bisexual thing among CSA survivors.
Good luck.... that's one of the more confusing issues to survivors. I don't even really have an answer for myself.