Don't get carried away by comments made on your post here. If you have good case of divorce on the ground of mental cruelty, please go ahead. Asking the husband to leave the old parents and not to keep them with him or take care in their old age has been considered as act of mental cruelty on the part of wife along with filling false criminal complaints against the husband and his parents and divorce allowed to the husbands on such grounds. You will be allowed visitation for both children even during pendency of the cases.
As far custody issue for both children is concerned, the Family Court has to consider the welfare of the children rather anything else, if the welfare of the children is best when they live with father, than father will be given their physical custody and mother allowed visitation for the children on regular basis and same vice versa.
The application under section 26 for custody/visitation of children along with section 13(1) (ia) HMA for divorce is preferred for now but the main petition for custody of both children should also be filled under the Guardians & Wards Act in the meantime.
As far the maintenance for wife is concerned that she gets only if she has no means to maintain herself, no job no salary or income, but if she is working and has sufficient financial means to maintain herself than she gets nothing, however the maintenance of minor children is responsibility of both parents and as father you must provide your share of financial support for both children yourself and show it in the court even in your application u/s 26 HMA as well the main child custody suit under the GW Act, this will show your good self and get you relief from the court while considering the welfare of your children.