不为负心婊折腰
[bù wéi fù xīn biăo zhé yāo]
It conveys an attitude that refuses to compromise or lower oneself for a disloyal, faithless person. Here ‘bitch’ is used to describe females of bad moral character, especially those who show betrayal easily in relationship and ‘don't bend the waist’ is idiomatic for showing submission or humbling oneself to such people.