Hi... yes it is correct here.

to cut someone with his/her explanation (/alibi), it's more likely to say: "please, that's enough..." or "please, I don't wanna hear another word..." (kinda rough though) :)

romulus is correct. or you can simply say "please stop" or "please do not continue".

I agree with Rokr. Normally, you would hear "Please, go ahead"...It is commonly used to encourage someone to continue. "Please, don't go ahead" sounds odd an unnatural. It is being used on purpose that way as sarcasm. The last thing the man wants in this situation is for the woman to continue speaking. I have a feeling she continued anyway. :)

I know "go ahead" can mean ask someone to continue saying something,but"don't go ahead" seems kind of not so natural to use it here even it makes sence.