Family life affected by schizophrenic wife

I married 18 years back (in 2006) and got my 1st child in 2008 who is 16 Years old now. After child birth my wife started behaving abnormally like not doing household works, not taking care of the family, only sleeping etc. Later she was taken to psychiatrist. She then was diagnosed as a schizophrenic patient and started taking medicines. But she did not recover and unwilling to live with me and demands money from me every month for maintenance. I asked why she married me as she was aware that she will not be able to maintain a family life due to her disease, then she confessed that she hid this secret from me and her parents also knew this fact and did not disclose to me. No I am paying her maintenance each month without any of her service or contribution towards my family. My child is staying with me and supports me, but my wife is staying with her parents and taking money from me every month. It seems they have cheated on me for sucking money only. I have been cheated. How I can get rid of this ? I need divorce from here. Please advice.