I'm sorry this is happening You sound like you love her a lot and she's lucky to have someone in her life who wants to help her and understand her.
I can't seem to find the way to help when she is all over in rage.
The bottom line is, you can't. Not when she is dysregulated. I'm sorry, that's probably not what you wanted to hear.
There are tools and techniques, though, when used together over time, that can come together and create a climate with less and less tension and less and less dysregulation. It falls on us to use those tools and techniques, like validation (and also pay attention that we don't
invalidate), time-outs, boundaries, using SET - support, empathy, truth - when stating an opinion etc. Sometimes we do it well, sometimes not, but even doing some is a lot better than doing nothing at all.
If you click on Stop the bleeding on the right, you get to a page that will take to to these tools.
--------------------------------------->
I hope this is of some help and comfort.