throw someone under the bus
US /θroʊ ˈsʌm.wʌn ˈʌn.dər ðə bʌs/
UK /θroʊ ˈsʌm.wʌn ˈʌn.dər ðə bʌs/

1.
echar a alguien a los leones, traicionar a alguien, sacrificar a alguien
to betray or sacrifice someone, especially to save oneself from blame or difficulty
:
•
He decided to throw his colleague under the bus to avoid getting fired.
Decidió echar a su colega a los leones para evitar ser despedido.
•
I can't believe she would throw me under the bus like that.
No puedo creer que me echara a los leones de esa manera.