A hiatal hernia won't kill you. My dad had one. My mom has one. It was suspected that I did, but I think I ended up not having one, or maybe they just never looked for it on my imaging tests when I had them in that area.
Anyway, it won't kill you. It's harmless. My dad's would occasionally be HORRIBLY painful, like heart attack painful, but it would last for minutes or hours and most of the time would be totally painless. That was the extent of the damage it could do.