Joel Turner's ShotIQ is THE system. I had target panic as bad as you, except with a trad bow. I am consistently competitive in 3D tournaments now with my longbows and recurves, and I can shoot animals without flipping shit. All thanks to Joel Turner.
This worked for me:
1. Draw, keeping your thumb in FRONT of the trigger (DO NOT move that thumb - it'll be hard at first)
2. Do NOT aim
3. Do not look thru the peep
4. Hold for 10-20 secs and let down - Do NOT shoot
5. Repeat several times
6. Do steps 1-4, but look thru the peep now - DO NOT aim at anything
7. Repeat a few times
8. Do steps 1-4, but add in aiming using a HUGE target with no pressure to keep the sight anywhere specific
9. Repeat as needed
This might take 1-3 days, but the mental link should be broken and you can resume normal practice. A back tension release might be helpful, but from my experience just changing your release won't fix the issue. You have to draw and let down without shooting so your brain realizes it's ok.
It's all about breaking that link in your unconscious....many ways to train yourself.....they all have the same element of drawing and not shooting for awhile.
Jim Casto on AT has a free program he gives out that works....