You say you're only 15 but you have not mentioned anything about your parents. They must know what is going on and have an opinion?! Are they going to hand out the cash for feed, board, tack and training?
It really does take a lot of know how and experience to bring a horse back. Taking lessons at a riding school (if you even do that) is totally different to training your own, broke down horse.
Maybe you just need to relieve yourself, your parents and your friends of this expensive burden, and get the horses off to a rescue.