I didn't expect that she would stab me in the back.
to stab someone in the back直译过来就是：“在某人背后捅刀子”，这个短语很形象地表达了：“在背后中伤别人，暗箭伤人”。因此，当美国人说"I didn't expect that she would stab me in the back."时，他/她要表达的意思就是:"I didn't expect that she would hit me secretly."、"I didn't expect that shewould speak ill of me under the table."、"I did never think that she would injure me byunderhand means."。
Shirley: I didn't expect that she would stab me in the back. I placed too much trust in her.
Jane: Yeah. In order to get ahead, she works hard by hook or by crook.
①She can talk to me face to face.
②Moreover, I treat her like my best friend.
③It is unfair competition.
④If I were wrong, she could point it out directly.
1. speak ill of 诋毁，说……坏话
Don't speak ill of others behind their backs.
She never speak ill of anyone in his or her absence.
2. under the table 秘密地
Some athletes sometimes cheated, sometimes lied, or took money under the table.
The matter was finally settled under the table.
3. by hook or by crook 不择手段
Unsuccessful people eager for quick success and instant benefit only care about yourimmediate needs, even by hook or by crook.
Since this was going to be the decisive game, they were determined to win it by hook or bycrook.