I still refer to my ex-wife as "momma" in conversation with my children...?

I think your wife is being petty and not thinking of why you do this.......for your children only. Would she rather you called your exwife honey and darling and her mommy. Since you can't seem to resolve this by communication I would suggest a trip to a marriage counselor. Telll her you love her too much to let something so important to the kids and unimportant (should be, that is) to her to let it affect your marriagw. There are so many more important issues to work on than something basically sillly. I commend you as a father for being sensitive to what's best for your children. The world would be a better place if there were more fathers like you.