Yes, my surgeon said that too, that people do just live with them.
I did have pain with mine. I don't know how to explain it! Umm, it was similar to the pain I've had post surgery, a really deep, draining pain. I couldn't use my stomach muscles to sit up and coughing and sneezing was agony, like post surgery. My surgeon said the pain was probably due to food pushing through such a small tunnel, my MRI scans initially showed that the fistula tract was absolutely minuscule.
I can't say why your husband is getting so much pain, especially if he is hardly eating. Sounds like you may need a second opinion.
I had medium output from mine, between 60-160 ml a day. But I was told that if my output went over 300 ml I would need TPN as I'd be losing nutrition. It is good that your husband's output is low, I guess because his is lower down in his bowel?
You're very welcome. They're tricky, miserable things these fistulas. Sending you both my best wishes. X