Despite my recent posts indicating I'm slow on descents, I go over 40mph regularly. Also, I know exactly how you feel. I wiped out years ago at high speed -- got knocked out even with the helmet, lost some teeth, have permanent scars. For quite awhile afterwards, riding at speed scared the crap out of me.

My advice? Don't force it. Riding fast is like walking on a roof or dealing with dogs. If you're scared, your chances of problems increase drastically. Just ride the way that feels right and as time passes, you'll find yourself gradually speeding up again. If you relax, you are less likely to make mistakes and your body will help you adjust to problems that pop up.

I agree that it sounds like you hit your brakes too hard. The faster you go, the more gentle you must be. Sometimes your best option is to control your crash rather than try to avoid it entirely. This takes more mental discipline, but it really makes a huge difference.