Agree with Paint :). Larger barreled horses take up more leg so a smaller size might work for your combined heights...15.2 or better. Smaller barreled horses, like thoroughbreds, don't take up as much leg so someone who is really tall, or long legged, would need a larger horse.
I am 5'6 and my horse is a 16.2 Thoroughbred but he is built more like a stockier Trakehner. I have been on horses, quarterhorses, at 15.2 and had no problems. If you compare it, at 5.8 you would be the same height as a 17 hand horse; your husband, 18.1 hands.