Sounds like you have a fair idea what's going on actually, but just lack the confidence & skill to turn it around on your own. So don't stress, you haven't 'ruined' him or anything, you don't need to give up, just get some instruction/help with him. Especially if you believe he *was* well mannered & trained, he is likely to be perfectly OK again, so long as you can become consistent and assertive. So if you can get a trainer to come instruct you on how to handle him, that's the way I'd go.
Don't know how old your daughter is, gathering she's pretty young if you got her a shetty, but she may be old enough to start learning some safety basics too, so you have a little less to worry about(tho I dunno about you, but I didn't know what worry was, until I had kids... esp around horses).
On your above post, 'so he knew he could rule me', yes, horses work out very quickly what works & what doesn't. But you can be 'bossy' without confidence & get nowhere either - horses need a leader to feel secure, and if you're not it, even(especially?) if you're pretending to be, they may feel the need to step up, or get anxious & reactive about having no trusted leader to rely on. So again, I'd suggest working with a trainer, to learn how to be *confidently* assertive.
Re the whip thing, sounds like he knows that if he steps out of line when there's a whip in hand, it will be very unpleasant, so he's motivated to avoid that. And he has obviously found there's no good reason he should do stuff in absence of the whip - he doesn't get punished if he refuses, &/or he doesn't get rewarded for doing 'Good'. So you need to make sure you can be effective with him regardless of what you're holding - make the Right things Good & Easy for him and make the Wrong things difficult & ensure they don't work for him.
You might have noticed I said '*Good* and easy' and I've mentioned rewarding him for 'right' behaviour. Negative reinforcement(release of pressure/removal of unpleasant stimulus) is an invaluable training 'tool'. But don't discount the value & effectiveness of positively reinforcing(reward/add something desirable) the behaviours you want to encourage too. Just as the pony has obviously associated the whip to the fear of punishment, you can associate Good behaviours with Good consequences, to have him actually keen to do what you ask, rather than just because it gets too hard if he doesn't.
NB forgot to emphasise, until I saw Dancing's post, that yes, I agree that while it's far from 'panic stations', I would indeed be treating this seriously & making it a priority, especially when you're planning on bringing up a foal. At least the gelding started out well trained - imagine when you have a young horse with no clue, if you still have little ability/knowledge to teach him either, what a mess that could be.
Last edited by loosie; 02-13-2015 at 07:53 PM.