How to get over my fear of horses?

I have always loved horses and help a friend out with some ponies. The other day she was teaching me how to lunge one of the ponies who is very young (4 years) she is only 14 hh but is like a mini tank. It was going quite well and i was really enjoying myself when she turned her head and decided to escape out of the school she started bucking and ran off and i was pulled over onto the floor. It was only a baby mistake which i understand but today we decided to lunge her and my friend Maggie (came 3rd,5th and 7th in the royal welsh so she is amazing with horses) started lunging her and i was literally shaking i really didnt want to do it. when she passed the lunge line to me i got scared even if she just shook her head. i wasn't even hurt when she ran off but im just terrified to do this. Maggie even said how it had dented my confidence. is there anyway i can get my confidence back so i can enjoy my time around these great horses thanks x