How to express in one sentence the feeling of being stabbed in the back by someone?

1. What I once believed in deeply is now changed.

2. If sincerity is exchanged for betrayal, why should you be sad? What should be happy is that you finally recognize the truth.

3. Friends are not meant to be betrayed! Commitments need to be guarded with life. Courage is not the absence of fear, but the courage to move forward despite fear.

4. You once said that friends are trust. I nodded, planting the seed of trust in you in my heart. But as soon as it sprouted, you ruthlessly pulled it up. The seedling of our friendship withered, and my heart was broken.

5. Break up with friends as soon as they break up. Don’t talk behind your back. When she was good, she worked hard for you. Don’t tell everyone she’s not good. It’s not good for people to trust you back then. Be friends with you? When friends turn against each other, it's a matter of stance. What they say and do after the turn turns against each other is a matter of style. It's okay to have no friends, but it's not cost-effective to have enemies.

6. Friends are easy to say but extremely difficult to make. Sometimes friends who are smiling and cheerful one moment become tense enemies the next moment. Regardless of interests, power, or righteous reasons such as family, country, and world, it is possible for two friends to go against each other.

7. I don’t need friendships that are fading; I don’t need to get to know friends who betray friendship at will; I don’t even need friends who treat friendship as a game.

8. A person who betrays friendship is using you to help him achieve his goals.