You would be able to sell your life estate, though it would be difficult at best to find a buyer for just the life estate. Because all three names are on the deed (and your son and daughter-in-law are married) all three of you must convey and release their interests in the property by signing a deed to a purchaser of the land.
If you have a life estate only and your own the rest of the interest in the property, you can only sell what you own in your name. I would consult with a real estate lawyer or real estate company about your options before you decide what to do.