Long story short I pushed when I should have backed off and she panicked and tried to jump the round pen fence. Tried. Failed. Flipped over the top of it and broke it. Had the fence not given way, she could have broken something :( I'm terrified she might have as I have heard stories about young TB's tripping and breaking their necks and then not showing signs of injury until days later.
Just remember, everyone makes mistakes. A few months ago I did something really stupid, it was so scary. I was sure Lookit was going to get hurt, but thankfully he didn't.