不在乎有两种英语译法：1.not to mind;

not to care;

to be unconcerned about;

to be reckless of

2.unconcernedly

根据意思只能用第一种（not to mind;not to care; to be unconcerned about;to be reckless of ）

I don't care about it.

I do not mind it.

I am unconcerned about it.

I am reckless of it.

改一下：I haven't cared about it already.&I have not already minded it.I haven't been unconcerned about it already.&I haven't been reckless of it already.

对某事的不在乎可以在mind和其他短语介词后面加从句

如I haven't cared about that you had a mistake of understanding of me already.

about 等介词后还可加代词和-ing形式，如I haven't cared about having a talk with that girl.