I would like to know if my best guy friend is gay?

hmm, that is quite a dilemma. There is some pretty substantial evidence of him being gay but there is also a possibility of him simply being a straight guy with a feminine voice, its not unheard of. Honestly the only way you can know for sure is if you ask him, and given his sensitivity with the subject, I can see why you are reluctant to do so, but Honestly, I think you should just show him this question. It reflects how earnest your feelings are for him and displays your turmoil. I think were he to read this, he would understand where your coming from and if he's straight, it might be the start of something real with you two and if he's gay it might prompt him to come out, at least to you.