Hi Albatross,
While your specific situation is unlike mine, the behavior seems similar especially this.
She herself told me multiple times that she was no longer my wife and what she does is none of my business and now she seems so jealous and spiteful Bc I finally moved on.
My BPDx was the queen of double standards. I was to comply with one set of behaviors (whatever she wanted, when she wanted) and she another (whatever the hell she wanted whenever the hell she wanted to do it). So it's not surprising she said she didn't care, and now she does.
All the other crap aside (and there's plenty I can see here my friend), my advice is to keep your relationship "downwind" from your ex and not give her any more fuel for her erratic behaviors. Play it cool for a bit, and she'll likely soon get bored and some other impulse will drive her to do some other wild and crazy thing (hopefully not involving you or your backyard lawn furniture
. So if it's things on social media, maybe don't post about your new relationship, etc...for a bit.
Another reason to keep your new relationship on the QT is that your oldest daughter may become an inadvertent messenger of disturbing news. It's not good to put your kids in the middle, especially with an unstable ex. If you can, maybe don't do "date night" on nights your exchanging kids with your BPDx. I'm sure your co-worker will understand and she doesn't want to exacerbate the situation, right?
You're wife's a manipulator, of course she's going to do the daddy thing. Your daughter will know the difference. My father tried the same thing when I was seven and my sister 4 with our stepmother (our mother very much alive and we lived with her). We knew the difference (and she soon will). One battle at a time.
There's the other forum board too, about divorcing with kids, those folks might be a good place for specific references to your situation. Good luck