@oristarA,
oristarA wrote:
Not very clearly got it.
You've done it = you've finished it?
You've gone = you've lost?
1. "Now you've done it!"
You need to consider this as a complete phrase. It is slang and here means "Now you have done or said or written something which annoys me (or will annoy somebody else)", although I think dadpad was being jocular.
2. The slang phrase "gone and" is used to express exasperation at a reckless, careless, thoughtless, foolish or otherwise deplored act; they do not affect the meaning otherwise. It does not imply that the person physically "went" anywhere.
I allowed you to drink out of a valuable glass, and now you've gone and broken it! (and now you've broken it and I am angry)
I told Jim that Mary was pregnant and he promised not to tell anyone, but now he's gone and told her mother! (now he's told her mother and I am angry)