how do i stop panic disorder?

Just want to encourage you and by all means start perfecting relaxation techniques.
For example: resting in a recliner and repeat a word (ex. 'One') over and over as you breathe.
As anxious thoughts fly up.. focus again on the word as you say it.
Try to work up to about 15 minutes twice a day.

Basically, take care of yourself just as if you had a cold or a flu as you will eventually get past the withdrawal phases.

Good on you!