1) in your reply mention that wife family had suppressed material facts of her illness and played fraud upon you
2) you can file for annulment of marriage on grounds of fraud
3) anullment should be filed within period of one year of discovery of fraud
4) in the alternative file for divorce on grounds of mental cruelty
5) wife refusing to have sex amounts to mental cruelty
6) you can file case of cheating against wife and her family members under section 420 of IPC
7) also file complaint of criminal defamation against wife and her family under section 500 of IPC for maligning your reputation
8) court would in divorce case direct you to pay maintenance to wife