I couldn't help it !!!

'I couldn't help it' means I am really bound to do it, না করে পারিনি, করতে বাধ্য হয়েছি

Conversation

Daryl: I am upset. Somebody told my boss I have a part-time job.
Smith: And he doesn't like that ?
Daryl: No, he doesn't. He thinks that I am too tired to work.
Smith: I am sorry. I have to admit I told him.
Daryl: You told him ? Why ?
Smith: I couldn't help it. He asked me point-blank.


Explanation :
If you can't help the way you feel or behave, you cannot control it or stop it from happening. You can also say that you can't help yourself.
If you say something point-blank, you say it very directly or rudely, without explaining or apologizing.