Horse Jumping and Trouble With Trainer. Help!?

So I lease every Sunday with my nest friend and I ride the most awesome horse (I have my own horses at my dads house, not my moms) and I'm with my mom but she doesn't see this. I do pony club with my horse, Sierra, nut she is my the greatest jumper. So one tme after pony club, I wanted a little more practice and there was a 2'8 jump set up (I can jump it my Sierra-little did I know- can't. So I went to jump it and she refused. I let her snuff it and stuff and tried again 4 more time. Refusal after refusal. So I tried again and she went over, but I wasn't ready for her to actually do it so I fell onto her neck and before I knew if she was scrambling. At first, I thought it was because I was .cloning on top of her neck like a maniac. Then I realized she was half way over the jump (I don't kno if her hooves were on the ground or not) and she scrambles backwards our of the jump, bringing it down. Then she stopped but I was still on her neck but she was chill. That's how I kno she didn't freak cuz I was on her neck. Don't worry, she is completely sound and wasn't hurt a bit. I am just wondering what happened? Did she freak and stop the jump cuz me landing on her neck startled her? Anyway, my best friend was there and saw the whole thing. She was telling me before I tried jumping it "No! Sierra isn't ready for it!" I ignored her though...(Sierra is about 15.1-15.2) I think she meant she thought Sierra just wasn't experienced enough. I slid back Sierra neck onto the saddle and then got off. BTW, the pony club instructor was there the entire time and saw the whole thing. So that was last Sunday. Now its Wednesday. I'm on vacay but my friend is still in town. Today I learned my best friend rated me out to my trainer! (BTW, Sierra is HER horse!!!) And now my trainer wants to talk to me. Supposedly, all my friend said was that I made Sierra jump something she wasn't ready for after pony club.(We are not supposed to jump when we lease, though we do it a lot anyway)