[annnnd]

This is the perfect answer! Nothing else matters in this situation. The only problem with the picture painted by OP is that he is reluctant to let go of control, which is exactly what he should have done a year ago, at least partially.

Nobody in the company should be irreplaceable, otherwise you have a single point of failure.

On a more practical side: don't work on your vacation (and I mean this in general - like ever) or it doesn't make sense to even go on one. If you must, you can try shorter breaks first so you get confident that the world is still turning once you get back. And do not answer phone calls during the breaks!