The recommended way is gradually diminish the dose over a two to three week period, the last week taking the smallest dose every other day, then stopping. Great idea to use the medication as you described, temporarily during a rough period, and then off once you have regained your well being.
You should always contact your doctor if you want to go off a medicine. Your psychiatrist can tell you how to wean off the zoloft. Going off cold turkey or too fast can cause serious side effects that can be avoided by following your doctors advise and instructions.
It might be wise of you to stay on the Zoloft for a few more months. It is generally advised to people to continue taking the medication, even if you start to feel better. SSRIs like zoloft can sometime take 4-6 months to provide maximum benefit, as well as long term correction. And you should know that 50mg is a relitively small dose for zoloft. On the other hand, if you still feel that you can cope without it, just gradually decrease the dose under your doctor's supervision. You have not been on it that long, so withdrawl symptoms are unlikely, along with the fact that Zoloft is generally not habit forming. The worst that can happen is that your anxiety/PTSS symptoms will return. From my understanding, PTSS is most effectively dealt with by means of pyschotheorpy. So if you do choose to stop the medication, and experience recurring PTSS symptoms again, go back to theorpy. In most cases, medication is only an aid, not a cure. The underlying cause to your emotional stress should be dealt with through cognative, and dynamic theropy to fully make ends meet. Good luck to you, and I hope the forum M.D. can help you further.
Do not take this as professional advice. I have no background in medical/psychiatric care. This information is based on persoan experience.