throw someone under the bus idiom
informal（为了个人利益）出卖某人|牺牲某人|背叛某人
to do something harmful to someone else in order to gain an advantage for yourself
He has been accused of throwing fellow Republicans under the bus for his personal agenda. 他被控因私利而出卖了共和党同僚。
I'm not going to throw my friend under the bus for something he did 25 years ago. 我不会因为我朋友25年前所做的事而背叛他。