Ann, І wіsh І hadn't donе іt...
Ann, І wіsh І hadn't donе іt!
&
Ann, I'm so sorry to have done it!

What is the difference?

Question

Ann, І wіsh І hadn't donе іt...
Ann, І wіsh І hadn't donе іt!
&
Ann, I'm so sorry to have done it!

What is the difference?

Answer

The sentence with "wish" expresses regret.  It's not directed at anyone and so it is not in itself an apology.  The second is an apology.  Normally, people say: "I am so sorry I did it."