That is a terrible situation, really sorry to hear about it.

I'm even more sorry to say you may well be screwed here. My wife is a Private Investigator so I've got somewhat of an inside line on this sort of thing. Obviously if he was DWI and rear ended you, he's 100% at fault so suing him is a slam dunk win for you. Winning is one thing, collecting a judgment is another thing altogether. You need to find a good PI who can do an asset search on the guy and see if he's got anything. I happen to know a very good PI who's excellent at asset searches, by the way. (yeah, yeah, shameless plug, but an initial search is quick and fairly cheap and I'd like to help if possible). Odds are the guy doesn't own anything of real value (house, land, cars, etc) so, again, collecting would be virtually impossible. Even if he does own a house, land, etc the best you could do is get a lien against said property and he wouldn't be able to sell without settling the lien.

Not a rosy picture, I know, but the a$$hole could have killed you in the wreck Fortunately he didn't. Things really could be much, much worse.