The original sentences are not correct (have grammatical errors). They can be rewritten as follows: 俺は一方的に君を傷つけた。I hurt you one-sidedly. 取り返しのつかない事をした 。I did something that was irredeemable. それを忘れて 、Forgetting (that fact), なかった事にしてくれなんて 言うとは、 and asking you to forget that it ever happened... 俺は本当に最低の人間だよ。I'm really the lowest of the low, ain't I?

@snow.d sorry for that. I post the original part just now.

I can hardly understand that as the sentence is not complete.