'외치고, 또 외쳐도 다시 돌아오는 메아리처럼 이런 내모습이 익숙해질까봐 너무 두려워' To help with understanding, it can be rearranged like this. 외치고 또 외쳐도 다시 돌아오는 메아리처럼, 이런 내 모습이 익숙해질까 봐 너무 두려워. It may be translated: (literally) Like an echo that comes back every time even if I shout again and again, I am so afraid I might get used to the way I am now. (with simplification) Like an echo that returns every shout I make, I am so afraid of getting stuck with how I am now.

even though i shout and shout again like a memory that comes up again (i dont know what 메아리 is so i assume you mean 메마리) Will I ever get used to this? it's too dark. (rough translation, I'm not a poet haha)