Should I have a 3some for my boyfriend?

My bf is bisexual and he wants me to have a 3some with him and a female! He said it has been one of his biggest fantasies to be pleasured by a man and a woman at the same time. I am questioning if this is a wise idea... If it happens, then I only want it to happen this ONE time. Also I am GAY and I ain't to thrilled about sharing him with a female, but I am not the icky type, who thinks girls are gross and got the cooties LOL.What would you do? Thanks for your answers in advance.