So, we have two characters. One is Mr. Superiority, and the other is Hayley's character. Mr. Superiority treats Hayley's character like crap, pushing her away, but refusing to let her go - blaming her for everything but not wanting to be rid of her. Basically, he is the one holding on, being completely selfish, and taking advantage of her patience. And then you can see that she's realized what is going on, and that she's incredibly tired of the way he is acting. "This is the last second chance," is like the confession that she's put up with it for so long and she can't just let it go on anymore. She's saying that next time he starts blaming her she's going to say that really he should be blamed. And since he thinks that he is always right, he's "playing God." It's the typical, "I'm getting out," scenario, but worded strongly and perfectly.