I think detachment is the key here. Not being nice, or not nice. Detached like she is a guest, like you would treat me or someone else sitting in your kitchen. Polite is not going to save your marriage. The more polite you are, the more you are likely to see cold and indifferent from her. It bites, but unfortunately the same behaviors are reported all over this board. There's just nothing you can do but let go. Hang in there! You've got this.
M-60 H-51 M-14 years BD 12/26/16 S 1/1/17
"First the pain, then the rising." Glennon Doyle Melton