My Brother's wife is having mental disorder and we filed a case

My Brother was recently married and during the married he observed some abnormal behaviors of wife and once she reached his home after married she(wife) started shouting, abusing and beating to family members and relatives .After such incidents we came to know she is having mental disorder and called her father .Her father tolled he was consulted only TANTRIK ,but girl told her mother use to give her medicine every day ,after this her father took her to his/father's house . After the married Girl only leaved 5-6 hours in groom's home in day time so that the marriage was still untouched. nWe have filed a case in family court within 10 days of time for null & void .Now girl’s father is telling that he will fine a case against grooms family for 498A.Please suggest what we can do in this case further and what is the possibility of null & void of marriage in such cases as we do not have any medical documents .