"처음엔 당신의 쉬크함에 반해놓고 이제와서 내가 뭐라그러다니" = 처음엔 (내가) 당신의 시크함에 반해 놓고 이제 와서 내가 (당신한테) 뭐라(고) 그러다니! = I fell for your chic ways from the start and look at me now criticizing you (about that). = It was I who fell for your chicness from the start, and I can't believe I said that to you after all this time. It has a tone of self-reproach. 이제 와서 내가 뭐라 그러다니 has a lot compressed into a short phrase. - 이제 와서(는) = (idiom) when we have made it all the way here. After after all that has happened. At this point. - 내가 뭐라 그러다니 = 내가 뭐라고 말하다니 = 내 가 뭐라고 그러다 + -다니 (verb ending expressing a surprise). - 뭐라고 그러다 = 뭐라고 (말)하다. It is literally "to say something" but means to call out something, i.e. to criticize. - 그러다니 = 1) (그렇게) 말하다니, 2) (그렇게) 행동하다니. It's not 그렇다+다니 (That would be 그렇다니). - -다니 can be considered a contraction of -다니 놀랍다/이상하다/못 믿겠다. It expresses a surprise, similar to (How unbelievable/unexpected) that ...". 그러다 means 그리하다/그렇게 하다, "to do that/so". It's often used in place of (말)하다 because it's more specific. When it has the -다 ending, it stays distinct from 그렇다 - 그러다 (do so) is a verb and 그렇다 (is so) an adjective. But when it ends with the -아/어/여 ending form, both 그러다 and 그렇다 become 그래 (그렇게 해 = 그리해 -> 그래, 그러하다 + -아/어/여 -> 그러해 -> 그래). So 너 왜 그래? can mean "Why are you doing/saying that? (action)" or "Why are you like that? (state)" (or possibly both at the same time). And the simple 그래 can mean. "Yes, go ahead and do that" or "Yes, that is so". It's also a common way to say "Yes, I agree".

Verb+다니 it's degree of outrage.

쉬크=시크=chic 이제와서 내가 뭐라그러다니 ; (When you give an opinion opposite to the preceding situation) Those words can be used when you suddenly hate what was good at first.