Sorry you've hit such a roadblock. I'm in the same sort of boat, except I'm "out", but she doesn't understand what I mean...
I think it's intentional on her part, though. Sound more like you've just had some stumbles. It's tough, it's terrifying, but... Got to do it eventually.
I'd ask, rhetorically, are you an introvert? Read that Introverts (like me) prefer to write things down for communication. Speaking is much more difficult.
I've found that to be true with my situation: She can talk circles around me, and once she gets started, she doesn't stop until you're trampled underfoot. Not just me - she dominates every social situation she can. Meeting for dinner with friends, THEY hardly get a word in edgewise.
So writing it out might be essential. Also, if you have a journal or diary, that might help, too... She could find it and her curiosity would likely get the best of her, and she'd read it... Get the message that way. Not good, but if you're already in bad spots? You do what you have to...
-Dianna