I have never had a fistula, but I have had enough surgeries to last a life time.
With any surgery, you need to allow yourself the time to heal properly. Let your body rest. We are more susceptible to infections because we have an autoimmune disease, so take extra caution when you are handling the incision. We are also more susceptible to getting hernias because it takes longer to heal, so use caution when lifting anything or bending. The smaller your incision is, the less likely you are to get a hernia, but it really can happen with any size incision.
I hope that when the time comes your surgery will go smoothly and you will be able to heal properly and move on with your life. Let me know if you have any questions!