I never imagined in my wildest dreams it would be this difficult
Ah yes, that took me back a bit. I did the rotary FI course, so it was a bit different. But I found it horrendously difficult, the whole thing. I was convinced I'd never be able to fly well enough, and never ever be able to teach anyone!!!
Looking back now, four years later, I can see that these feelings said more about me and my own lack of confidence than about my flying or potential teaching ability. And I wasn't used to being pushed to my own limits, by someone who flew better than I probably ever will. It was probably the best course I've ever done...though it definitely didn't feel like it at the time.
And instructing, which was hard in the beginning, got easier...and I love it!
Hang in there. And if you've got any more specific questions, ask on here. My friends on PPRuNe kept me sane during my course.