First off, you are EXTREMELY Brave for getting back on a horse after your accident. Most after an accident like that would completely forget about horses, but you didn't, and I want to congratulate you on your bravery.
Riding a horse basically like riding a bycicle. You may be rusty at it, but you quickly relearn how to do it. You know how to ride, and you can do it!!!
I have been on rides with a few people who have been in similar situations as yours. There is no simple "quick fix" for fears after a fall, but you can overcome it. I have seen it happen.
Have the owner, or another horseman you trust, ride the horse first, and do some groundwork with the horse before you mount. Don't feel like you have to rush into this. You should push your limits, but there is a point where you can't take anymore. Whne you start feeling/thinking, "This is getting to be too much for me", go back to something easier, or more comfortable for you to do.
The time before you ride will be the point where your emotions will build up. Do something that keeps your mind off of the fear and relaxes you. If cleaning the house distracts you, then break out the vaccume and pledge. If you want to talk to someone, bring a friend along (espically if its a long car ride to this persons house.) Keeping your mind somewhat elsewhere will take the edge off your fear.
Again I congratulate you for getting back in the saddle and I hope your ride goes well.