At 13, you are probably having all sorts of hormonal ups and downs that may feel like descriptions you read of being bipolar, but it's just your hormones trying to figure out where to go and what to do.
I envy you having horses. How many? Why don't you get to ride them? (When I was your age, my best friend had horses, so I hung out at her farm all the time.)
No one will adopt you at your age. The best you would be able to do would be get placed in foster care, and then you very likely will end up in a worse situation.
Tell me three good things in your life.