Poor Harry, he's so sick! And then Dudley burned him! :( I can't wait until Snape helps heal the burn though.. hopefully. It's really rich coming from vernon that harry's terrorizing his son. But so in character. You did a good job building up the suspense, especially with, "he heard his uncle on the phone, claiming to have a flat tire to explain that he would be late for work" and then Harry's fear.

This is kind of awkward phrasing: "When he looked back to his uncle, however, he immediately saw stars and found himself on his knees after his uncle raised the belt in his hand that Harry hadn’t noticed before, and brought it hard and fast across Harry’s face, buckle first." Usually just having an abuse scene with someone doing something for an amount of time isn't something that adds to the story, it actually detracts from it.

I think that there's enough horrible things in this chapter to not continue on, but you're the author. :)