Wow!
Dude, you are damn lucky that cougar didn't take you out. Scaring one is not a good thing, so the fact that he didn't swipe your torso in half while you were laying on the ground is a pretty good deal for you. That said, sorry you got hurt, and your bike is wrecked.
I've been a pretty hardcore cross-country rider for years, and I've never encountered a cougar. Bears a couple times, but no close calls. The one time, I was on a downhill, and my friend in front of me swerved to avoid what he thought was a bush in the middle of the trail. The bush got up and went bounding through the trees. It was a cub, so we got the crap outta there as mom was close by.