I imagine you would be able to track down a lesson barn in your area (I'm in Canada, so not much help). Think of lessons as a way to learn about riding, but also about horsekeeping. I have two dogs (in fact, have had dogs all my life, also, four horses and countless other animals). Trust me, even the hardest ones to manage don't even come close to being as demanding as a horse. However, horses don't live in your house, so there's that :) But the fact that you felt that instant connection means you should definitely pursue this! Maybe you can just spend some time at a stable, even volunteering to help with chores so you can see what it's all about.
It is a lot of work and a huge commitment, but the horse people you will meet in here will all tell you they would never even think of life without their horse - much like you couldn't imagine yours without your GSD. What you give to them, they give back to you tenfold.