This "discussion" doesn't have to be done on her timeline. In fact, it sounds like you've already stated your boundaries and the consequences for overstepping them.
All that's left is her attempt to bully/guilt/button-push you into backing down. Which is going to go exactly nowhere for either of you.
If you're doing what you believe is right by your values and your commitment to your own well-being and that of your loved ones, then you have nothing to apologize for. If you are calm and not angry, and are not trying to manipulate her into doing what you want, then you're on the right track.
You are not doing this to "hurt/punish her" although you can bet she will play up this angle. You are taking care of yourself and your finances.
She might not admit it, but I think she will respect that stance.
She's tired of "the ambiguity" and she "wants to talk when she gets home tonight"?
Sounds like she thinks she's calling the shots here, or at least, she wants to be and the fact that you are asserting yourself is p*ssing her off royally.
(Boy, this seems to be a theme this week, or at least it's a lot of what I've been reading. WAW trampling all over the place, acting all entitled. It's p*ssing ME off! )
I would not engage with her while she's angry. Period.
You already stated your case, no need to repeat it.
At most I would say: "I am not attempting to hurt you, however, I will not finance your... (insert whatever you'd like to call it here)"
Then close the discussion and don't engage.
Maybe have somewhere you have to be tonight...?
---(G)GGG
Me 54 Him 63 M 23 T 29 0 Kids Funny Farm of Rescues 12/12 OW-- 5/13 ILYBINILWY: A denied 9/13 Proof OW: ENDED 2/14 Got D papers on my BD I kicked him out for my sanity 9/14 He wants to "talk"?