Speaking as someone with a bad PGRE score... One of the first things I did to remind myself about my abilities is how half the people who take it need to, by definition, be below 50th percentile. It doesn't make you any less intelligent because it just has to be that way, and anyone who takes the physics test is leaps and bounds ahead of the general population to begin with.
Ok, that's nice, but what does it mean for you specifically. You say you've done lots of research and that's great- in fact, there are a lot of great schools out there that will weigh such a thing more carefully than a GRE score if it's out of line with everything else. Talk to your professors about what these programs might be, as you're probably not the first such case they've had, and apply to a good range of programs. You only need one to let you in, right?
And if not this year, well, there's always next year and one year really isn't a big deal. I needed to take an extra semester to finish my degree which I felt terrible
about initially, but now realize my application is all the stronger for it because I got a great summer research experience in I wouldn't have had otherwise, a completed senior thesis, a grad class, etc. Plus once I get my diploma in the next few weeks I'm off until grad school starts to do a trip around the world, something I always dreamed about doing but never saw myself as having the time to do. So all in all, I'd argue that an extra year was one of the best things that has happened to me in several ways, even if it seemed nothing like it at the beginning.