What is the meaning of もんな


Reading "プラチナデータ" by 東野圭吾.

Not clear on the meaning of:

> "俺、何度も彼女を殺しそうになった **もんな** " -
>
> "I often almost killed her ... (monna?)"

What is "monna"? I suppose "mono nara" ("if that thing"), but then I don't
understand the whole sentence - is it "If I often almost killed her"?




More than anything, it is a colloquial way of adding the nuance of
"retrospective confession or boasting" in my own words.

