<human>: He's my best friend and we grew up together and used to do pretty typical sexual experiments. We'd watch porn and jerk off together at 10. Then that proceeded to mutual touching, then eventually full blown sex.

This continued sporadically throughout high school, even while I was in relationships. He never dated and is now openly gay. I am completely straight but a horny bastard who likes having my dick sucked.

When I met my fiancee senior year we continued on for a while, but after we slept together I gave him up other than a few bjs in the adjustment period.

That was five years ago. I never cheated on her after that and love her. We are getting married soon. But he told me if I don't tell her he will. He says she has a right to know I am gay (am not) and cheated on her (five years ago). 

But if I tell her she may think I am gay and may not trust me anymore. This girl is my life. I don't want to lose her because of stupid shit in the past.

Could you distill the essence of the text into 1-3 sentences?
<bot>: my gay best friend I fooled around with as a kid is threatening to break up my engagement if I don't tell my fiancee about childhood gay sex acts, this can't happen.