Well, it does sound anti-climatic but doesn't mean it was for nothing!
Rest assured, there will be another conversation and another chance to hold your head high and make your proclamation again. Just because W acted proud and assured doesn't mean she IS proud and assured.
I've told the story of my 1st H on several threads. He was not only proud, but defiantly sure of himself. I went through a very similar conversation with him and weeks later, I got a letter from him about how I was the strong one...not him... that I was right, about everything.
Anyway, if you've read my history about that, you know he ended up begging ME back eventually and I said no. We were even divorced and he was living with OW and still was calling me and showing up at my office, wanting a 2nd chance...
Never underestimate the power of your words, but more importantly, your actions. Continue to GAL and be strong...
I know it's hard with your D. I went through something very difficult today too, so I understand. (Told S16 about his dad's indiscretions...)
You'll be OK. And DON'T let her tell you how to parent! You're the responsible one here, you don't need her telling you to watch your D in the water or anything else, esp. while SHE is threatening D's future with her current actions.