A friend of mine got nailed by a car in downtown traffic a year or so back. His injuries were less than you have but the bike was a write-off. He lost his nerve after that. He got a new bike, and I did a 4 hour ride with him shortly after and he drove over cautiously and was a danger to himself. Soon after he sold the bike and hasn't ridden again. Age wise I think that this was his first encounter with mortality, and he has young children to think of as well. Point being that all those factors add up to making a personal decision about whether to ride again or not. Same goes for you. No doubt getting back on the bike and working your nerve back up is part of the answer. I like the suggestion about taking a course.