Divorce and maintenance for domestic violence and cheating

My sis married for 8 yrs..her husband lives abroad illegally. he went there through my sis.. after he send my sis back India.have child also 7 yr old.her in laws.. continue harrased her for dowry..& did domestic violence.her husband is with other ladies ..that she know by through social media and friends. when she told her in-laws they blame her for adultery & kicked her out from home. her husband also not give maintenance & no contact..also they withdraw all money from her account..bcz her passbook with in laws...they bribed bank employees & & did fake signs.so now she want divorce...bcz we already go to police bt no help.so plz guide about divorce & ,lawyer fees ,child maintenance (she non-working)thanks.