Re: i need EVERYONES help, urgently.
OK, so what is he like to handle on the ground? Does he work well on the lunge and in-hand? Is he a gent to be groomed and handled in general including leading?
If he is brilliant in that respect then I would say there is either pain in relation to being ridden, be that teeth (bridle) back (saddle or you) or something else.
On the other hand if the problem have is if this is 'learnt' behaviour for avoidance then unless someone really experienced takes over your relationship with him will be difficult to get back in line.
He sounds just like my british warmblood mare, she is a dream from the ground, bit funny about vehicles but that it because she was hit by a car, however you get on her and her personality changes completely she becomes a demon. In desperation 11 years ago I sent her away for re-schooling and I went with her in case I was some of the problem, first yard gave up after a few months! I found somewhere else and same again only I was told to breed or shoot her but forget trying to ride let alone compete her. She had everything checked, twice when it came to tack by different people and saw numerous dentists, farriers, physios etc but physically she was fine, so whatever is going on with her is in her head. I doubt she was 'learnt' behaviour as I had her as a 4 year old and she was like it as soon as she arrived and if I am honest, she ditched the rider when being demonstrated to me - but I had already fallen in love!
Sometines you do just get a horse that does not want to be ridden and it becomes safer for everyone to accept that and do something else with it - everyone said I should breed from my girl but I felt if she had these 'issues' she is wrong stock to breed from, obviously having a gelding you don't have that option. Even though he was cut late he would get over being a Stallion unless the job was not done properly - have you had him tested?
I think if you have a real bond with him then it's worth checking out everything and maybe get someone else to ride him whose really experienced, at least then you can see if you are some of the problem. I had too with my girl and tbh it was great to see her go into full bronco with other people, at least I knew it wasn't just me! If you are really fed up with it all then find him an experienced home where he can be re-schooled or a 'companion' home. I would hate you to end up like me, wanting to continue but ending up totally loosing your confidence - I have hardly ridden anything since my accident on my girl which is when I called it day on her working life!
Good luck with whatever you decide.
There is no greater gift than to share time with a creature of such beauty - The Horse.