It's HIGHLY unlikely to be a reverse thread... sounds like it's been quite a while since it's been changed.
Sometimes when all else fails you can punch a screwdriver through the filter body and break it free that way.. but you do need some space. How about one of those "cupped' socket wrench fittings that fit over the end of the filter itself?
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)