背信弃义

背信弃义 [bèi xìn qì yì]

1. ■ treachery; act in bad faith; act perfidiously; be guilty of perfidy; break faith with sb.; break one's faith; break one's word and forget one's benefactor; go against one's words and obligations; have no sense of gratitude; perfidious involving a breach of faith; perfidy; play false; show one's bad faith; treacherous:

背信弃义地撕毁协定和合同 perfidiously tear up agreement and contracts