It's actually because of this?!Told you already that you can't change it so stop struggling!
或
It's actually because of this?!Told you already that you cannot get rid of it so give up!
第二句还是可以用...you cannot get rid of it so stop struggling!用give up(放弃)只是另外一种说法.
如果是想表达更完整一点,我想你前面应该是说:
I cannot believe it's actually because of this!I told you already that you cannot get rid of it so stop struggling!