dude just read through your post and have to say "so fucking what if you've slowed down a bit" we have a sense in our brains and its called self preservation, being taken out by someone else and then a bad crash on the road will effect any rider, and bolloxs if they say it doesn't that just pure lies
I had exactly the same reaction after having a crash 3 years ago where i got a corner wrong and had a head on with a tree on the opposite side of the road, should of been dead buddy.
new bike and couldnt ride it for toffee
You need to go back to basics, if that means dropping groups then so be it just accept the fact and then it will be easier to get over the fears that keep popping up buddy
either it be inters or novice at least you wont be being pushing into riding fast to "save face", get back to entering the corner slower and winding on and coming out quicker, it will start to come back slowly but surely buddy
hope this helps bud, good luck too