Irish please don't take this the wrong way. It is meant to be helpful or at least my thoughts on it.
Your W did a nice thing. For someone reaching out sending flowers was a step in the right direction. It was a good occasion and she seized it.
It was inappropriate of her to mention not being her choice.
The reaction of your D was understandable but probably disproportionate to what occurred. Your W triggers negative reactions in your girls. Who would blame them. I am not sure how but if it was my girls I would try figure out how to reduce the affect of such triggers. In a polite way help them detach.
I am sorry this almost ruined her big day and am glad it didn't
Best wishes
R 25 years M 14 years S11 & S13 Working on it alone since Oct 2014 M in trouble a lot earlier (~2 years) Feb 2016. 1st R chat in a yr. Next R chat Aug'17 Still together