Joe-Joe, thank you for sharing a clearer picture. I can totally relate. I have ridden since I was 5 and ran my own small horse farm. I became disabled and have been unable to ride for about 6-8 yrs. I have worked very hard at getting better. This summer I decided to work with my 31yr old stallion. It was as much for him as it was for me. He has been stumbling a lot lately. I put him on senior ultra and started some easy ground work to help him regain his balance. One day I slipped on his back to walk around. I was scared that even a flick of his tail would send me sliding to the ground. He was hesitant and I was a wreck. All worked out and after a week, 2 min turned into 10min. I totally understand.
I think you are right that he is feeding off your anxiety. Especially as he seems very in tune with you. Can you have someone lunge him while you ride? I did this a lot with students to get them to relax. You can just drop the reins and learn to relax again without worrying about where you are going or how fast.
If you would like to contact me directly please do. I may be able to help more but feel it is out of the forum topic. Best of luck
We are caretakers of the earth and the voice for those that don't have one