A divorce on mutual consent will be a quicker and cheaper process and you will not be required to make your personal matters public as it might be required for divorces on other grounds.
Divorce on mutual consent is covered under Section 13B of the Hindu Marriage Act, 1955. Under this provision both of you will have to show that for the past one year you have been living separately. This essentially means that for the past one year, even if you were living in the same house you did not live as husband and wife and had no intention of performing your marital obligations (Sureshta Devi v. Om Prakash, AIR 1992 SC 1904). The Section allows the Court to give you a time of minimum 6 months to 18 months to re-consider the decision (Suman v. Surendra Kumar, AIR 2003 Raj 155).
With respect to divorce on the ground of adultery, you will have to show that your wife had sexual relations with another man after the marriage with evidences. The DNA test of the child will be helpful to prove the ground and the divorce may be granted to you.
You have the option of using any of these two ground but in case of divorce on mutual consent, you can avoid disclosing the sexual realtion of your wife to the Court where the matter will become a part of public record.