Two years is a long time for a guy to wait for a girl to kiss him, and while I sympathize with this guy and understand your concern for him, I think that now would definitely be a good time to be honest with him about your sexuality. You’ve already told your mother and sister, and that’s a good start, but your boyfriend needs to know as well. After all, isn’t it better for him to know that you’re a lesbian and just don’t find yourself attracted to guys GENERALLY, rather than wondering
if it’s something wrong with him, SPECIFICALLY?
He’s got to be wondering what’s up, and while I would advise against telling him that you felt sick when you kissed him, you should let him know that you’re just not into guys. Tell him you think he’s a great person, and that you appreciate how patient he has been as you discovered your own sexuality. Explain that you would like to be friends, if possible, because you value your relationship with him,
even though you don’t have the sexual chemistry you originally thought you would. He may reject your friendship at first, feeling like you’ve led him on, but hopefully he will get past this and you’ll be able to remain friendly.
It’s always hard to break up with someone, especially if you still care for them. But you know that this relationship isn’t meant to be (at least not in its current form), and you need to tell him how you really feel so that you can both move on and experience the fun of sexually compatible relationships.