What can I do with mealy peaches?
Slice, drizzle oil, sea salt and freshly ground pepper and roast for 20-25 mins. Drizzle with good balsamic vinegar and enjoy. Actually, I don't know that this would make the mealiness less apparent but worth a try. I did this recently with some nectarines that had sat in the fridge too long and shrivelled a little. They turned out very yummy!
For just you to make the palatable:
puree them. I do this and the rare occasion we end up with mealy peaches they are fine. I put on top of my waffles in the morning as a healthier alternative to syrup. You may need to add a bit of juice if they are really mealy.
Make them into a dessert - cooking them will help. I find they can sometimes be gummy, but they work fine.
No need to toss good tasting fruit just because it isn't perfect!