One of the first things they teach a new swimmer is the “dead float” or “dead man’s float.” It is described in this way because the swimmer floats face down, back up in the water. Watching it, it resembles a dead person floating.
But the primary point taught here is not to panic. Float this way, then, when needed, push your arms down and bring your head up for air. No panic; no anxiety. The air is there when you need it, and you can continue to float this way (provided that the water is not freezing.)
Remember this now, in times of potential panic. Float and accept until action is needed. Provide action to survive. Don’t give in to anxiety.
You will survive.