cheated

I want to know is it possible to take some one in court. If some one made so many fake promises and made some one mentally unstable so that he has ho go through depression and he leves his house and tries to attempt suicide. Actually one of my friend is going through this. He had a very good friend from last 5 years and his friend washed his mind and promised him lots of fake things. He even has proffs where his friend accepted that he is responsible for his condition. Now my friend is completely mentally unstable and just want to die or walk away from home. Tried a lot but he can't understand a single thing. So is it possible to take his friend in court as he is responsible for his mental position and trust me my friend has lots of proofs.