I also suggest Parelli Level 1, the SAFETY Level, which is a home study pack of dvd's & written material. You need all your holes filled in re: how to stay safe, while developing your horsemanship skills & educating the horse, & a thread can't fulfil that need.
Picking up local horsey people at the tack shop is an iffy proposition if you don't know enough to know who's able to help your horse! You could also end up in a legal mess if someone gets hurt while dealing with the horse.
I find that your mare shows much relational capacity, & a sound mind, as you've described her, so I feel that, with your gaining the skill, a happy relationship is attainable. It's not the recommended pairing (green humans & green/difficult horses = usually disastrous results), but someone of high persistence, intelligence, & a love for the horse in question can prepare herself to deal effectively with the horse by a course such as PNH, or working with a qualified mentor.