I hope you can find some alternative ways of keeping him in your life. If you are struggling to get that money needed to buy and keep him to the level that it appears, you might not be in a position to own something as expensive as a horse. There are so many unexpected expenses that you have to be ready to deal with. I wonder how you will manage that. Have you thought about that?
Do you have the support of your parents? (I assume you are young enough to still be living with them).
Maybe you could partial lease him?