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You have done nothing wrong. You bought stocks--in 401Ks, mutual funds, whatever. Stocks go up and they go down too. Economy is good, stocks rise. When the economy is down, stocks go down. When the economy improves they will go up again--so long as the companies do not go out of business. Stocks are an important way to "inflation-proof" your portfolio--ie, if there is inflation, the value of stocks will track and give you better return than CDs or Bonds.
You don't need the money now, right? You're some 20 years away from retirement. If you look at historical cycles, you'll see that we seem to be on a 30 year boom/bust cycle. Hang tight.
If you were retired now, I'd say you should worry. But you're not. You're going to be OK.
For your own peace of mind, educate yourself about finance. Read a "Finance for Dummies" book. I took a finance class in my local community college--very low level--that at least taught me the lingo. I subscribed to financial publications for a few years, just to learn the culture and the language. (Barrons is good. Forbes used to be, but then they got all political.)
And DIVERSIFY. If you're 100% in stocks, put some in bonds. Put some in CDs. A little cash maybe. Spread it around some. When stocks are down, other things are not. (My portfolio has been buffered the last few months by a nice counterweight in high quality corporate and US bonds. 2 years ago certain people were scoffing at me for not getting high returns--but today if I had to sell, I have bonds that are worth something.)
If you get a financial advisor--with or without hubby--tell him/her you want to "depression-proof" your portfolio. Maybe you'll want to look at funds that invest in blue chip stocks. Maybe you'll want to add bonds. Or precious metals. The idea is to diversify so when your stocks are down, something will be up.