Beelady,
I FEEL for you!
I tend to be more cautious than necessary when I am biking. When I drive my car, I always anticpate that there will be a deer standing in the middle of the road around that next turn, and I try not to drive faster than I could brake for that. I anticipate wrong moves by others a lot.
From your description, it sounds like you may have been taking that 90 degree turn faster than your skills could handle if anything went wrong....which it did.
I try not to go faster than I feel confident going, but hey that's just me.
I do like going fast sometimes- but only when there is nobody anywhere in sight that might do the wrong thing! (DH doesn't count- he never does the wrong thing)