Agree with Cherie, namely that you're in over your head
. I prefer starting horses more non-confrontationally & I believe it's extra important to keep confrontations to a minimum if training donkeys, if at all possible(I have no experience with mules... aside from riding one down the Bright Angel Trail
of the Grand Canyon when I was 20yo
But now you've already started along that line & it seems to have brought out the worst in her, assuming you don't have time to patiently work on changing her attitude first, IMO you need to get her restrained effectively & then ensure you're effective at teaching her the lessons you want her to learn, rather than allowing her any more practice at the lessons already inadvertently taught.
Today I smacked her on the nose with the end of a buggy whip ( I had no crop) and that seemed to stop her pretty well.
Yep, IMO sometimes strong punishment is appropriate. It is a bit of a 'pitstop' in that it (if effective) will stop a behaviour in it's tracks, but generally only temporarily(unless the animal has no motivation for the behaviour). Therefore I'd think of it as a 'buy you time' tactic.
The corner I put her in, she busts out and gets her leg hung in the gate at times. The more she breaks out, the worse she is at charging and acting ugly.
It was probably being reactive out of fear when she was cornered to begin with. The behaviour worked for her, so with every 'practice' she's getting 'better' at it.
Boss wants to have her broken to pull a buggy when I get done with her (if I ever can). To heck if I'd get pulled around by that lunatic!
Inclined to agree with your sentiments the way it's going
, and I wouldn't trust her not to stew on it until she works out a way of getting the upper hand(she is half donkey, after all!) if she's 'broken' with manhandling, but IME even 'crazies' can become well mannered & reliable when trained considerately & effectively.