Are you still paying spousal support to XW? If so, that should be a nice bonus for you when she gets married.
I too am getting nervous about meeting GF40's large family this Sunday for their church thanksgiving feast. The mixed culture thing never bothered me with STBX (Thai) or GF40 (Vietnamese). I am more concerned about the diffences in religion (I am not religious) and whether her family is going to have difficulty with that. Her father is a Lutheran minister in 2 churches and her family is getting suspicious that she has been spending a lot of time with a mystery guy (me). I have met a couple brothers and we get along great.
You need to be there with you W the whole time she is with your parents so as to smooth over any awkward moments.
