Mutual divorce And Child Maintenance

Wife in relationship with some person and on the same agreed for mutual divorce. She is asking for the custody of 6 yr old child and maintenance to bring up the son.she is admitting that she will marry the person once divorced.question is a) can she seek custody of son when I am not willin to give her b) she is seeking maintenance for son till his college days even though she will be marrying a new person..do I still need to pay maintenance..is the maintenance until she gets married or life long even though she gets married to a new person and keeps the son.?