Hi
To "spill one's guts" just is to say what you are thinking or what you know, so the extra phrase isn't needed..
- I’m sure Kendall is going to spill her guts after SM made those demands on her
It's very idiomatic, of course, and I don't think it often uses a preposition..
- When the police get hold of him, he's gonna spill his guts
But not usu