What To Do For A Patient With Mental Problem?

My father is a mental patient since last 40 years. He had got doubt to my mother. Without geniuness he is telling and imaging the matters. He connected 3 to 4 of our relatives and telling bad relation with my mother. Sometime he is very violent. Nearly 2o years back we approached a Psycologist and he suggested a medicine DEplat 75mg, E. When some problems showing give this medicine. Last few years when this tablet given some face reactions appearing i.e. lips are going to one side and all.... so we are afraid and not given that tab. One year back he had a Heart attack - Silent. As per Cardiologist 3 blocks are there. Bye-pass surgery need. But the health condition is not good - Diabetic and Blood pressure - not yet surgery done and continuing Medicine (No circulation problem is shown in the Anchiogram). Medicine given for heart disease is Deplatt 75mg, Ecospring AV 150, Mono Isordil SR 30, Semi Daonil for Diabletic and Betacard AM for BP. Now few days he is very violent and creating problem/quarrel with others. We have not approached a doctor because if he know he will agains create problem. If we give the earlier medicine (mental) any problem will occure? He is 73 year old, Height : 5 8 . Weight : 78 Kg. Kindly advice us....