sell someone down the river
US /sel ˈsʌm.wʌn daʊn ðə ˈrɪv.ər/
UK /sel ˈsʌm.wʌn daʊn ðə ˈrɪv.ər/
1.
to betray someone for one's own benefit, especially someone who trusts you
:
•
I can't believe he would sell me down the river after all we've been through.
•
The politician was accused of selling his constituents down the river by voting against their interests.