The signature obtained by police in wps has no legal value as anything recorded in presence police is inadmissible in evidence in any Court under Section 26 of Indian Evidence Act, 1872. The statement cannot be used by police or wife against you as if the same is produce, police will be in trouble. You can file an RTI application but police will reject the same stating there is no such statement recorded. This statement will only prove that police are against you and taking instructions from wife. police will not use this statement in any Court. It only for creating fear in you. It will not affect your chances of anticipatory bail application. There is no need to draft any mou/agreement.