@iLevan,
I don't believe that someone "in love" can have a crush on anyone. Someone dating only can. You moved in 1 month into the relationship, neither of you hardly knew each other.
He has told you obviously that his is Bi, did he tell you that by living with him, you both are exclusive only to each other?
You entered that relationship knowing of his past. It's natural to me that it would haunt you into your present and future. Any little trigger is going to make you snoop. I don't think this relationship was thought out very well from the inset.
My opinion is this. Stop snooping. What will be will be. If you snoop you'll get all sorts of mixed messages, not converse with him, back away from him, ruin the relationship. If he cheats, he ruins the relationship. You'll find out one way or the other. Concentrate on the relationship itself and hope that you didn't enter one whereby you are going to be cheated on, rather his " don't worry" is reality. There is such a thing as fantasy.