Mark, my advice would be to hold the line, hold the line and remain strong.
Add to your "don't get into R talks with her" this:
DON'T GET INTO "L" TALKS WITH HER.
Simply say "since this is a legal matter now, it's probably best left to the attorneys to handle that," or "Draw something up, and I'll have my attorney take a look at it." Stay civil and calm.
Basically, your position now is "There's nothing to talk about relationship wise, since you chose to end our marriage and to invite a third person into it." And "since I'm not an attorney and this is now a legal matter, ________ is best handled by our attorneys. I'll discuss it with mine, and we'll get back to you."
