Codependent riding

The picture is only because I haven't posted one in a long time.
Today I had a good ride on three of Mike's horses:
Falada - Grand Prix
Tempi - Baby
George - 4th Level
Then I had a lesson on Willig, where we reverted to our work two years ago ... going past the scary corner. Seriously.
Mike gave me some more tools in my tool box to work with Willig (other than the unsuccessful losing-my-temper approach). Interestingly, although done in their own styles, his and Shannon's advice has been pretty much paralleling, and I'll call it "stop being a codependent rider."
Here's what seems to be happening: Willig radar beams his ears onto the scary corner and tenses up. I tense up my hands. He feels my tension and tenses his body. I feel the tension in his body and tense my body. He feels the tension and is like "oh shit! I better run!" As he takes the first step towards run, I go from 0-60 and start ripping on his face - that just scares him more. You get my point.
So both Mike and Shannon in my lessons this week had me do something that is almost physically impossible for me to do ... let go.
Shannon had me do it in the riding-with-only-my-seat method.
Mike had me ask Willig to connect (and then LET GO - I have a freakishly hard time letting go) and then once he gives, let go until his head pops up or zings around again. It's "ok" (not desirable, but as a training tool, ok to do for the short term) for me to use hard hands - what I'd call sawing on his face - if he ignores me and tries to crane his head around like a giraffe. But as soon as he gives to me, I have to stop and have light hands, even if I think he's going to fling it around a nanosecond later.
So we did that for a while around the corner. (We also did it at the end of the lesson, where Willig immediately - despite almost an hour of working around that corner, after being away from it for 2 minutes, flung around again like an epileptic.)
Then Mike set up a tiny little jump to see if Willig would rush it like he has been. No. He didn't. He jumped it from stupid take-off points, but was all ho-hum (going around the corner AFTER jumping it? That required counterbending and shoulders leading all crazy tilting-boat to the inside. But the fence itself - yawn.)
Mike did notice that I have a death grip on the reins, so even when Willig jumps, and most likely when he's heading towards a normal sized fence, I'm clenching tighter and tighter - which Mike points out gives him something to lean forward onto and REALLY rush. So again, his advice was to ride to the fence, and then LET GO and just let him do his job.
Then he turned the fence into a ground pole and we worked on shortening the stride and lengthening the stride to it and in between, to work on those take off points that Willig is missing. (When I started on the show jumpers, we told them the spot, and after about a year, I could always see it. Eventing, I try not to tell Willig the spot so that he'll find it - or correct it - himself, because I'll need that more on xc in case of trouble than I want a pretty sj round.)
Then we did just a bit of lateral work and ended with some canter work. Mike has noticed I have a fast seat - I'm not surprised given the rest of my personality - and so he had us work on going from an even trot to an even (excruciatingly slow) canter then when I ask for it (1-2-3) back down to even trot (or walk or halt).
Then, as I said, we rode back down to the far end where Willig was scared, and then when I walked him outside to cool him off, birds flew, which made him spook again. (By the by, most of my lesson was with the mower going just outside the door, which made for a great opportunity to work with Mike while Willig had something he was scared of.)
It was a useful lesson, but frustrating. It doesn't feel like we're making a lot of progress on the riding-neurotic-willig front, and I don't understand why I can ride Mike's horses (he pointed out his horses SHOULD be better than mine, since he's a professional and makes a living doing it, so maybe I should rethink my standards), but not Willig, although he and Shannon both pointed out the past history probably has a lot to do with it.
It's just that - Mike's horses, as varied as they are, are fun. Willig just feels like work.