She knew she was my lifeline, so she cut the rope, watched me fall to my 
death, and laughed.

She is entitled to nothing less than the same.  He knew he was her 
lifeliine, so he cut the rope, watched her fall to her death, and laughed.

Isn't it an irony that things didn't turn out that way?

I didn't die, but she did.

HA HA HA HA HA!