I Am Under a Lot of Pressure

My personal failures sort of seem to stem from my horseback riding. I've been riding for about five years now, and am nowhere near the level I should be at. I hate trying new things, like jumping a line, (two jumps in a row) mostly because I've fallen a lot. I tend to overthink everything I do in riding, and as such, I almost always fail in some way. Today, I did a new thing - jumping a diagonal, vertical jump. I hadn't done it on Red, the horse I was on, and was quite happy about it. My instructor then asked me if I wanted to jump a line, and I said no. Last time I tried that on Red, he refused the second jump several times and then bucked, and I almost fell. So when I'm heading up to the line, I'm getting flashbacks of the time where I almost fell, and have been terrified going up to lines, and have pulled him out of it. I was feeling worthless after the lesson, and fell into this little black hole that I seemed to have made for myself. I told my mom when she came to pick me up after riding, and she yelled at me for it. She said that I was doing so much better at my old barn and it's been three years since I was there, therefore, I should be cantering whole courses now. I told her I was afraid, that I didn't think I could do it, and she told me to "just do it". As if it's actually that simple to conquer something that your mind is telling you will kill you. I told her it wasn't that simple, and she just brushed me off and kept yelling. It made me feel worthless even more than I already was, so I ignored her the rest of the way home. Every time she asked me a question, I answered with a cold, one-word answer. Eventually, she was quiet until we got home. I always tell her for things like this to try and take a walk in my shoes, but she never listens. She always goes on and on about me not being able to do anything, and how I'm such a coward. I don't understand it. She hasn't ever been on a horse and had her mind convinced that she's going to die, so what right does she have to lecture me? She's always pushing me to do better, to be better, and I'm not sure how much more of this I can take.