Originally Posted by DiabloScott

Slow down, come off your saddle, put your weight on your right foot/pedal while leaning to the left, put your left foot on the ground as you stop, keep holding the brakes so the bike doesn't roll.

Now you are stopped with the brakes on and your left foot on the ground, your right foot still on the pedal, and you're straddling the top tube. All you have to do is figure out the best way to get your right leg back over your bike.