I appreciate the fact that you are trying to make it easier for your daughter, but allowing your soon-to-be ex to run over you in the process is not making it easier, for anyone.
If you have trouble doing it then advise your lawyer to act on your behalf.
Frankly, your soon to be ex sounds, um, unstable and I’m not sure she is the best person to have custody of your little girl. True, we are only getting your side of the story, but it’s sordid enough without her input. Please remember this: when you disrespect the spouse or ex, you shame the child. So, keep your animosity (well founded) to yourself. It will be hard as hell sometimes to bite your tongue around your daughter, but over time, your calm and common sense will win out over your ex’s apparent love of drama and shenanigans. Good luck–and stop giving her money!
I have no advice. Although count me in with Lord Ashtar’s comment - people actually look me in the eye and ask why I’m afraid of marriage. All the same, I wish you luck in everything, DYM, and hopt it works out best for your daughter.
You have to be. A short bitter divorce will be easier on the kid than a long protracted bitter divorce. Bite the bullet and get this over with quickly.
And stop being nice. It just makes it worse in the long run.