Sweetie. Unless you have uncommon physiology...
Have you TRIED to swallow your tongue? Not suggesting anyone should try, but I find that because it is attached to the floor of the mouth, I can't even shove it back far enough with a finger, to even begin to do anything that would cause distress. Many things might create sleep apnea, but swallowing one's tongue is likely a very uncommon occurrence unless you have an abnormality in the flesh that keeps it in your mouth, or it's been surgically altered.
For me, this is the kind of thing- or even more so- than my intrusive harm thoughts. Which I have to practice disregarding. I remind myself that they're ridiculous because otherwise I'd have acted on them long ago, and I'll worry about it when it's happened, and not before. Which requires effort and the ability to set the thought aside. Which takes practice. There's nothing special or magical, and no special skill on my part, I just have to practice.