I feel for you nuge........I had some bad target panic at the beginning of this season. Like you, I do well at the 3D range, but put meat in front of me and I waws falling to pieces. The last deer I shot I looked at the horizon before I drew. It calmed me down a little and helped my form in that I drew horizontally, then bent at the waist - something you're supposed to do from a treestand. Looking at the horizon had a dual positive effect for me.

Good luck.

Say this 3 times before you draw:
"Pins and needles...needles and pins it's a happy man that grins"

this may sound silly, but start telling yourself there's no way you're taking the shot. its the same method i use to jump into icy cold swimming holes up here - "There's no possible way i'm getting in that water." i say that to myself even as i'm jumping and my body doesn't freak out. so maybe saying " there's no possible way i'm taking this shot." with your brain and body 'tricked' you'll do things just like in practice. works for me, but i'm a sucker for reverse psychology.