I appreciate your concern about my recent diagnosis. I did a little more digging and it turns that a "sliding hiatal hernia" is not very serious. Put it this way: if you had to have a hernia, this is the one you'd pick.
More details may be found here.
I'll quote the prognosis section, which should put your minds at ease: "The outlook is excellent. Most people with hiatal hernias have few, if any, symptoms. More bothersome symptoms usually are controlled with medications."
Grateful for: my lucky hernia.