I read a few of the "pause" tutorials on here but wasn't really happy with them. Here's what I did and it seems to work.
I created an animated sprite containing two animations in it of 1 frame each and I called it "pauseButton". Animation one is called Pause and is the standard || Pause icon and animation two is called "Play" and is the standard triangular Play icon.
The rest should be explained in this graphic:
Clicking/touching Pause freezes everything but doesn't disable touch input. I've only tested it with the mouse but I have no reason to believe it won't work on a mobile device.
In your particular case you could replace the touch event with a timer event.