I wanted to [...] him—to let everything out.
What's a common word to use in this cases?
I'm looking for something similar to
spit as in
to spit something out. Like, when you say something harmful to someone because of anger.
Out with it is a common expression when asking someone to reveal something.
Tell me what you know !! Come on , out with it!!
or just to reveal the truth
to utter suddenly or inadvertently; divulge impulsively or unadvisedly (usually followed by out ): He blurted out the hiding place of the spy.
Perhaps you are looking for vent.
He vented his anger on her.
How about confess?
I wanted to confess to him.
Confess does not need to be preceded by anything because it is defined as:
admit or state that one has committed a crime or is at fault in some way.
So it would be confessing the truth. You could also consider some of it's synonyms: Reveal, disclose, admit etc.
I wanted to offload onto him -- to let everything out.
I wanted to get this off my chest to him -- to let everything out.
I wanted to pour this out to him -- to let everything out.
I wanted to give it to him straight -- to let everything out.
I wanted to tell him like it is -- to let everything out.
I wanted to come out with it. (if it is a secret)
I wanted to come clean. (if it is a secret)
I wanted to blurt it out. (if it is really bothering you and you want it out in the open, but this case implies there will be some negative consequences)
I wanted to level with him. (if he has a misunderstanding of what 'it' is)
I wanted to set the record straight (if he has a misunderstanding of what 'it' is)