I think you fell for the "real estate never goes down" and "a home is your biggest investment" BS that's floated around by groups with a vested interest in doing RE transactions. A house is just another expensive doo-dad, same as a car or boat.
Yes, I've had a number of other investments that lost 50% of their value. Several small holdings in various tech stocks lost much more than that. A LOT of people lost 50% of their investments in stocks in the recent downturn, though they have some of that back if they stayed in.
You seem to be unwilling to say even a city or state, and without that its hard to say what's going on. I think many areas are not going to see big continued declines. There may still be a few boom areas that are still going to feel some pain.
You're unwilling to say what you could get from a sale, so its impossible to advise you whether renting is a good idea. Personally, I like to see cash on cash returns in the high double digits for rentals. In this case, "cash" is what you could net from a sale, which is about 90% of the selling price. If rents are $1500, and you net $750 after all expenses (yes, they're that much, read in the Rental Property forum), you're netting $9000 a year. A 15% return would imply a value of $60,000. If you can sell for more than $60K, sell.
OTOH, you have a place where you can live with nothing out of pocket. There's a lot to be said for that. I keep my rentals fairly highly leveraged, but my goal is to get my residence free and clear.