Don't worry about IPC (498a) or DV (civil) cases. After 7 years magistrate won't take cognizance of dowry harassment. 498a can be still filed for general cruelty, but will get station bail for sure. As for DV case, she won't get much out of it and she will also have to run for court equally for it. If she files contested divorce, it will take 4-6 years to get the result. In the end, she won't even get the divorce, because courts RARELY give divorce when couple have kids. She needs very strong, horrible case to get divorce when they have kids.
Also, your friend can also file for visitations, custody etc., as his right (actually he'll have to) which will make her run around courts with two kids also. In two years, she'll be so bored, she'll forget about divorce.
Summarily, tell your friend there is nothing to worry. If she wants to go legal route with cases, IPC cases and divorce, let her. She'll have to face equal if not more trouble. If she files false 498a, that will go against her both in contested divorce petition and also child custody petitions.
I do suggest not agreeing to divorce for the welfare of kids. That triangular story (wife, husband, lover) will not work and his life will become from being on the frying pan to being on the stove directly.
