Adivice

We have taken the mutual consent divorce, first motion on the 27-decmber-2020 and second motion on 05-january-2021 and final decree received on 08-feb-2021. As per mutual consent and decree I have taken the child custody as a guardian and father for child education,social and cultural etc. And once three months my ex can meet the child which is mutual agreed and same is mentioned in the final decree. My child is 30 month old.now my ex wife is Demanding the child custody and she coming to my house and giving harassment to me and my family. The divorce is taken mutually from the court and passed by the judge how she can ask the child custody,also ex saying as per law upto age of 5 mothers custody is must. The divorce is taken because of the my ex having affair which I have cought on whatsapp adultary messages and phone records, as I am out of town 8 months. She is govt employee hence my ex father in law suggested we will go mutual consent divorce as her character will spoil and job issue (affair having with Person married and having 5 month girl). I also agree for the mutual consent because,she is not asking the property, alimony and child custody also awarded to me. Now what I can do in this case.