If this is what you want, then you should be prepared to be open and communicative with your BF. Tell your BF everything, because he'll know if you're holding back (maybe not consciously but at some level he'll know you're withholding information). You know your BF deserves this. But you deserve it too. I made this mistake in my past, not telling my SO about an emotional relationship that I had while I was married to her. Big mistake. She has forgiven me but I never will look at myself the same way. There is a black spot that spoils my self image, and I don't think it will ever go away.
So be fair to everyone, spill the beans and tell all.
Take the risk of thinking for yourself, much more happiness, truth, beauty, and wisdom will come to you that way. - C. Hitchens
Me: Male, bi, 48, flexible