There's a mite on my queen. Say what?

Today I was thinking about how many strange things I say now that I keep bees. And when we found a mite on the queen in our TBH, thinking about how funny an outsider might find the statement, 'there's a mite on my queen,' was the only thing that kept me calm. When Tim told me that the hive didn't seem to be doing so well generally, I came home at lunch to check things out. Sure enough--the hive really seemed to be languishing. Not as many bees as normal, not as much traffic in and out of the hive. I think some of this is pretty normal; there is always a lull when a new queen takes over. Many of the adult bees die off before the first of the new queen's workers emerge and build up numbers. But when I opened the hive, I found an unusual number of workers with deformed wings and saw several workers with mites on them. The final straw was noticing a mite on the queen. I actually believed that this couldn't happen. I thought that the workers would keep the queen mite-free at all costs. But I guess at some point, the bees lose the battle and they can't protect the queen. Now we are trying to figure out what the best thing is to do. Should we let the hive die and take their not-so-mite-resistant genes out of the gene pool? Should we treat them and try to save the hive? Should we re-queen and let the remaining bees contribute to a potentially healthy future hive? If we re-queened would the new queen just get attacked by mites too? I am constantly surprised at how much the well-being of our hives effects me emotionally. It really is disturbing to see such lovely, helpful creatures weakened and destroyed by parasites. I know it is all part of nature, but it's very sad. And it seems to have happened so quickly--before the hive swarmed 5 weeks ago, everything seemed to be going along swimmingly.