Choctaw County marriage records begin in 1907 when Choctaw Co was created at statehood. You'll have to look for Choctaw Nation records. I'm not aware of where you might locate them if they even exist.
Antlers and the Sugar Creek (Nelson) area were in the old Pushmataha District, Kiamichi County of the Choctaw Nation. A map of the political division of the CN can be found on the county genweb site at: http://www.rootsweb.com/~okchocta/images/nation/small-nation.gifhttp://www.rootsweb.com/~okchocta/images/nation/small-nation.gif
If you'd like to contribute Kate's obit to the county site I'd be happy to put it online.