打(う)ちのめすto knock down, to beat (someone) up, , to injure (someone) so badly they cannot recover (esp. emotionally), to overwhelm (with mental anguish, etc.)

辞書の定義

五段活用（サ行）, 他動詞
1. 1.
  EN to knock (someone) down, to floor, to beat up
2. 2.
  EN to deal a devastating blow (from which one cannot recover), to devastate (emotionally), to crush, to overwhelm, to defeat resoundingly, to give (an opponent) a drubbing