As a child who *has* know they weren't straight since a young age, and been afraid of telling their parents, let me first say that for him to tell you in the first place means you're doing some things right - it means he trusts you enough to let you know.

Your son may be confused about his sexuality, it's a confusing thing to figure out, *especially* if you aren't heterosexual! But I urge you not to tell him that he's confused, or to doubt him, or to write this off as something that could be a fad/phase. One of the most important things you can do for a bi/gay/queer kid is take their feelings seriously, and love them for who they are - not in spite of who they are. I know that some parents are afraid of mentioning the topic once it's been brought up, because they're scared of "encouraging" those feelings, but please don't feel that way. Nothing you do, one way or another, will change your son's orientation, you can't "accidentally"(or purposely) make someone gay by telling him it's an ok thing to be. What you CAN do, and what I think is important to do, is let your son know that regardless of who or what he is, you love him, and that it's safe for him to figure out and not hide who he is around you. And as a final note, PLEASE, PLEASE do not tell anyone else about your son's sexuality unless he says it's ok for you to share - if you led him to believe you wouldn't tell your wife about it yet, make sure to check in with him and let him know before you do tell her. It's very sensitive, personal information that he's trusted you with, please respect that!

Is there anything specific you're looking for help or support with? Having been in a position similar to him (though I'm older in my 20's now, and not male), I'd love to help you and him both out if I can.