I applaud your courage in expressing how you feel. It's wonderful to have the support of your friend but things always get tricky when you develop feelings for straight friends, regardless of their cultural background. You have two options and they both require serious thinking on your part. If you're certain that your friend doesn't like men and you express your feelings for him, you might get hurt because he can't reciprocate those feelings. Also, it might shift the dynamic in your friendship and that will lead to further hurt.
I would say, play it by ear. Don't act upon your feelings now. See if he continues to touch you, lean on you, etc. If his joking-around intensifies, simply say in a very casual tone, 'Hey, wassup with you? I thought you were straight. Are you looking to switch teams?' Say this in such a light-hearted way that neither one of you will feel offended. You'll both have retained your dignity and friendship no matter the outcome. No one loses.
Hope that helps:-)