stab someone in the back
US /stæb ˈsʌm.wʌn ɪn ðə bæk/
UK /stæb ˈsʌm.wʌn ɪn ðə bæk/

1.
背叛, 暗算
to betray someone, especially a friend or someone who trusts you
:
•
I can't believe she would stab me in the back like that after all we've been through.
我不敢相信她会在我们经历了这么多之后,这样背叛我。
•
He felt completely betrayed when his business partner stabbed him in the back.
当他的商业伙伴背叛他时,他感到完全被出卖了。