You're not throwing money away, you are basically getting to buy your shares "on sale." You are essentially getting more shares for your money now and when the marketbgoes back up, you will make a much higher return. The BEST time to invest money is in a down market. That's how you make more money in the long run. Stopping your contributions now could cost you tens of thousands of dollars in 20-30 years.
The absolute BEST way to invest is to contribute monthly and never look at your balance. In the end, you will likely come out way ahead but the ups and downs can make you go crazy thinking you "lost" money. Look at your investment rate of return from when you started your contributions. Is it a + rate of return? If so, you haven't "lost" anything.