I think CorsairMac and Deb W have great suggestions. Instead of having to unclip suddenly at the bottom of a steep hill with a hard right coming up, give yourself lots of practice on a flat, quiet course. Clip in, clip out, a gazillion times, till your body starts to have the movement memorized. And I would like to point out that people also can, and do, also fall when they are using flat pedals. I had a classic fall like that two years ago, when I was off the bike at a stoplight. It was a heavy bike, I lost control of it, and it knocked me down. Please note that I had both feet firmly on the ground when I did this. And yes, there was an audience. Wish I'd sold tickets beforehand!

I've been using frogs for a year and a half now and would never switch back. Let yourself practice a lot in a relatively safe setting, and you'll get there.