I'm sorry for what you're going through. First off, never force yourself if you're truly afraid. That could make matters worse. Maybe once you're feeling more sure of yourself, start off slow and stick to just groundwork until you feel confident to take the next step. Hopefully you'll be able to find a horse that you trust and perhaps just stick to grooming for awhile. Then once you feel more secure with that horse, move to walking him/her just down the barn aisle at first, then farther and farther. Walk him out to graze eventually. Keep it simple and relaxed. Go at your own pace and don't feel forced to do anything based on other's expectations. Even if it takes months to move from one phase to another, who cares?! Don't feel pressured by others no matter what. If you feel you are, maybe you're not at the right barn.
I can somewhat relate. I fell and had a bad back injury awhile ago and didn't want to get back on the hotter horses I was used to riding until my back was healed. I hate to admit it but it did shake my confidence more than I thought initially. I left behind the show barn I was at and decided to take some time to do my own thing and not force myself to do something I wasn't comfortable with. I was fortunate enough to come across an old QH at a rescue who had spent the majority of his life at a dude ranch. He was quiet and nothing really ever spooked him. He was so skinny when I first adopted him that I couldn't do anything with him other than groom him until he put on some weight. I spent about a year with him, starting slowly with groundwork and then just rode him on the trails enjoying the gorgeous scenery in my area. I was nervous riding him for the first while, thinking I couldn't handle another fall and injury. We kept it really slow, sometimes I'd only ride for 10 minutes. I stayed at a walk on him for a long time before I had the confidence to pick up faster gaits. With time, I was able to get my confidence back and am now back to my old habits of riding my young horse. That QH was truly invaluable with helping me get my confidence back. I am so blessed to have found him!
Another thought... I have a friend who was in a similar situation awhile ago as far as lack of confidence goes..... she wanted to get back to horses but didn't want to commit to a purchase or even a lease until she was sure she was comfortable again with it. She posted on craigslist.com and a few local horse forums looking to go spend time grooming and walking someone else's horse. Suprisingly, she was flooded with responses from people who have horses they didn't want to sell but currently didn't have the time to spend with them and would love to have someone come and spend time with their horse for free. She visited several horses before she found one she was comfortable with. After time, it really helped her get her confidence back without having to truly commit. She has since bought a horse and is a confident rider again.
Obviously we're all different and have to approach our fears in our own way. I'm sure you're trainer is wonderful but perhaps even her quieter horses aren't the best fit for you at this time. Maybe look around. Maybe find an older QH or draft/draft cross (they're usually laid back).
I wish you the best no matter what you decide. I hope your daughter's elbow is feeling better!