lose yourself

So I'm sort of writing, as I have been, but the problem is that I keep getting immersed, and I don't have time.
I've had a flurry of ideas. I pushed aside the one novel, the one i've been calling Barbarians_Novel, because I was spinning wheels and needed to go into something else for a bit. ( tortuous saga of my creative process )

My problem with my creative process isn't so much that I don't know how to write, it's that I don't know what to write. I can't figure out which part of this story would be the most worth telling. It's pretty much all come together in my head, but I'm sort of wondering... well, where should I pick up the story?
Because my imagination never presents me with a story, it presents me with a whole reality, and what part of it to write down is never something I'm totally clear on.

This isn't something beta-readers do for you, is it? Help you figure out which parts are worth writing?
And how can I get someone to help me with this? Because I just don't know whose story to tell.

And is "tortuous" really a word? Google says yes. Hm, how long have I been writing it "torturous" and mis-using it?
Depressing.