It's unlikely that the washer fluid will do any damage other than increasing the freezing point of the coolant some. Also, mixing between the recovery tank and the rest of the system is a rather slow process as the fluid from the overflow tank only gets drawn in to mix with the coolant in the radiator, hoses, engine, etc when the car cools off after being driven and the first stuff drawn back will probably be mostly normal coolant pushed into the recovery tank when the car heated up.
I'd recommend sooner rather than later siphoning all the stuff out of the coolant tank -- or simply removing and draining the coolant tank if that's easier. Don't worry too much about the liquid in the tank. It's toxic, but it's biodegradable. If you spill some, dilute it with a lot of water and forget it.
Refill the overflow tank to the bottom ("COLD") line with an appropriate antifreeze.
If you live someplace where it gets REALLY cold, you might want to check your coolant at the radiator cap with a hygrometer just to make sure that you haven't unduly compromised your freeze protection.