The begining of the rest of my new life? (3)

[Ripe]

Yesterday, Monday, the kids and I came home after the fabulous weekend.
On Mondays the kids stay with their mother, but because we were arriving a big late and they had school the next day (today) I told them maybe they could stay with me and that we should ask their mom. Plus, I had bought a Playstation game, so they obviously wanted to play it.
As soon as I crossed the border I called STBXW. S7 immediately told the mother they would sleep at my place. STBXW became upset and told me she was expecting them and should be consulted before such changes of routines. I agreed and told her S7 had assumed wrongly. Because STBXW was becoming more and more upset I cut her and told her to expect the kids shortly. I explained the kids they would be with me the following day and, besides S10 saying "separation [censored]" they understood.
I took them to their mother and talked to her outside of her door. I told her I would never take any decision concerning the kids without talking to her before.
To my surprise she was extremely angry and bitter.
She said incredible things like "Whether you want it or not I will always be their mother and even if you don't like it".
I never know how to react to such speeches and, besides trying to validate as best as I could, I did nothing.
Poor STBXW.
She lives by herself since October and one would expect for her to be already in a better place, but no.
And she has been like this since I told her we would not be friends after the divorce.