We had a Standardbred race horse that was a great money earner. With lifetime earning of 250,000 by the time he was 4. But he had one really bad habit severe agressive behavior on the ground. I have gotten one too many bad bites where I bled threw 4 layers clothes. I tolerated it for a long time but he got worst. This horse was never mistreated nor spoiled. He was just whacked. One day he charged at a groom walking by his stall and actually busted down the door knocking the groom over and breaking his left arm and two ribs. That was it we had him destroyed that day. Its sad but it happens.
Im sorry about your situation. Its not a easy one