What a wonderful story Ryan. And you're right, once horses are in your blood, you can never quite walk away!
It's all about "balance." You can do it! Just decide what you're hoping to accomplish with each -- should you decide to get him. So, if it's showing the minis, you know how much you must do for showing. Then, consider the riding as therapy 'just for you." You can diversify, and still find time for both. You just need to set out what you hope to accomplish with your little ones, and what you're really wanting to accomplish with him.
We have great faith that you can take time to figure out what works best for you. We have to have "lives" too, and if riding him gives you pleasure, than figure a way to work him into your schedule....just for your pleasure. If you find yourself not spending enough time with the little ones, and it bothers you that you're not spending enough time, just adjust your schedule to accommodate both, or decide it wasn't the best idea, and find him a home. But, spend some time pondering....there's no rush is there? If not, just take the time you need to make the best decision you can. Goodness knows, sometimes what we think is a good decision, turns out wrong. But "no harm...no foul" as the saying goes. You just make another adjustment and keep on going!