To be completely honest, it's the internet and people saying rude thing about you/your horse is most likely going to happen. You just have to be the bigger person and not let it get to you.
I've had people tell me my mare is so fat she must be pregnant (LOL, if they think she's fat I'd hate to see what they think is a good weight!), I'm fat and need to loose weight, my mare is worthless and never going to get anywhere. And that was just in one post. HAHAHA. All of which I know is completely untrue. What other people say has absolutely no affect on me. Some people just like to try and stir up sh*t for the fun of it.
I'm sorry rude things were said about your horses, it hurts but YOU know your horses better than anyone, just try your best to brush it off. :)