My advice would be to hide out for the summer away from as many of your social contacts from your high school doing all the things you listed above. When you return to school in the fall come back looking distinctively different from how you look now. Maybe get a drastically different hairstyle, or get a good tan and get into awesome shape, or just have an entirely different wardrobe or a combination of as many of these as possible. People recognize physical change long before they recognize social/emotional change. If you look different people at your school will be more willing to accept that you ARE different.
Think of it as a social metamorphosis. If a caterpillar wrapped itself up into a cocoon and came out looking the same looking only slightly different and improved it wouldn't be that big of a deal. You need to come back to school with some social butterfly wings.
~Antithesis