Horses= Unending Patience! What my experience tells me, is for you to continue what you are doing, the slow road to low poles, and positive reinforcement...When you are successful at any level of walking over, and over, any reward you use to let them know that was good, can only help to rebuild confidence all around. The very slowly, add a little more to get back to where you left off..
The problem in front of you, is part you...As I have been down this same road, I remember time and time again, I was more concerned (even afraid?) of giving up, almost did many times......Then nobody wins. For them, a bad experience is one they will often choose not to repeat...Then it is up to you to try with all the patience and time you can muster to show that they Indeed will survive very well the very same situation, even with very simple repeat steps, and your own confidence...Often it is a matter of mentally stepping back from this situation, and looking at it as if it were happening to someone else...It often becomes clearer what you will need to do then
Best of luck, and TONS of patience to you Lw