What word (or expression) can I use that means “to break someone's lie”?
I mean to aggressively point out that she or he is lying.
She stood up and ___ his lie/that he was a liar.
I'm thinking of debunk, but it doesn't seem suitable here.
You may want to consider using divulge or the phrase brought to light. Although, they are not very aggressive. A more aggressive term would be brand. As in , "She stood up and branded him a liar."
You might say you "exposed" that person as a liar.
That works mostly if it is to a larger audience of people. It loses some power if it's just two people arguing in a kitchen. I guess the connotation is that this person was lying to many people, and you "exposed" her to all of them.
Consider "to call someone's lie":
There are times when a subject may try to misinform you, even utter lies. In such cases, you don’t have to call his lie.
Another possibility was suggested in the comments: to call someone out (on their lie.)
I didn't get mad, but could tell he was lying and later called him out on it.
Also to call someone on their lie can be used (omitting the preposition "out"):
Why did my boyfriend get so mad when I exposed his lies?
So, why did your ex-boyfriend get so angry when you called him on his lies?
(In the example above, the first line is a question, and the second is part of the answer restating the question in different words. I highlighted "expose" and "call out on" in bold to demonstrate parallelism. To show they mean the same thing.)
to prove a statement, opinion, or belief to be wrong or false
"She stood up and refuted his lie."
She stood up and denounced him as a liar or She stood up and denounced his lies.
You could even say I denounce you as a liar! or just You liar! or You lie!
When said strongly, additional words aren't really needed.
From Merriam-Webster (www.merriam-webster.com/dictionary/denounce):
1 : to pronounce especially publicly to be blameworthy or evil
And less so, but related:
3 : to inform against : accuse
The word decry was mentioned, and is possible, but to me is not quite right, because that is (Merriam Webster) express strong disapproval of which isn't quite the same as saying that someone is lying/wrong/etc. (The person could be telling the truth and you still decry him.)
You could give him the lie
To charge with falsehood; as, the man gave him the lie. [Webster's]
She stood up and dismantled his lie. More aggressively: she tore his lie apart or she made mincemeat of his lie.
The first word that came to mind for me was: busted! Growing up in Southern California this was a term I heard all the time when someone was exposed as a liar.
Similar to give him the lie, you can give the lie to [something].
She stood up and gave the lie to his claims
I would use "see through". She saw through his lie.
In some situations, "revealed" can work: "She stood up and revealed his lie".
However, this can imply that there was some preparation, and/or that the lying happened in the past. The reason is that "to reveal" means to make visible what was invisible before.
Shakespeare said, "to give someone the lie direct". The "lie direct" is a bold and barefaced lie. Accusing someone of the lie direct is a big takedown.
I would like to propose "outed" or "indicted" as follows:
You could also say that you "caught him out in a lie". That might work without being too extragavant or dramatic.
I would say something like this:
She stood up and called him out on his lie. She stood up and put him on blast for his lie.
Another good word would be 'refute'. It's similar to 'debunked', which you had mentioned.
Refute: prove (a statement or theory) to be wrong or false; disprove.
You could also use 'challenged' which is less assertive, or invalidate(d).
Just wanted to add another word: impugn, which means "to dispute the truth, validity, or honesty of (a statement or motive)" i.e "She impugned his pleas of innocence."
It comes from the Latin pugnare meaning "to fight", so it's a fairly "aggressive" word.
How about 'unmask'?
You could say 'she unmasked his lies' or 'she unmasked him as a liar'. It has quite a theatrical feeling and is probably more associated with something done publicly than privately between two people.