There are ways to deal with the digs and the emotional insults that are inevitably hurled by the people who know you best, when they feel that they've been wronged or when you're no longer sharing a bed with them. All bets are off about how people are going to behave when they feel as if they've been wronged. They either go away or they get nasty. No one is immune.
The way that Taylor Swift and Adele deal with these losses and their broken hearts are different than the ways that Kate Nash deals with hers. She's slightly more likely to do what Swift does to all of her old lovers and friends. Swift takes the position of almost always being the victim and the guy who used her and left her deserves to be publicly shamed in more of a vengeful way. He's made to look like a goon while Swift can continue to appear as the sweet girl who was inappropriately left. She'll be okay. She'll survive. She was sad, but not for too damned long. Adele takes the position of making the breakups and the pain feel debilitating and incredibly beautiful. She makes these busted relationships feel cinematically sad and that makes them tear-jerkingly epic. She's in much worse shape - binging on darkness and sullen walks, just trying to get her feet back beneath her.
The way that Nash goes about tackling the people who hurt her is to firmly scold them, as Swift would, but to also add some lightness to her claims. It's a bit like how Mike Skinner of The Streets would do it, if he were a woman, looking to make a guy feel like a shithead for being pig-headed and dense. Nash sings here about a guy calling her a bitch in front of all of their friends and making everyone feel a touch awkward, but she doesn't care. She's over all of it. She's over him and it's all just a foregone conclusion. His outburst wasn't the point of no return. It happened long before that and she'd already begun the winding down, dishing out some dirt herself. She embraces the shortcomings smoothly, knowing that it's better that she's moving on. She's not holding onto anything. She's just sweeping the floor, getting rid of the garbage.