You can go ahead with the mutual consent divorce with the conditions that the child will remain with you under your sole custody permanently and he shall not be entitled for visitation rights also.
If he is not agreeing to this condition then you can discard his proposal for mutual consent divorce.
You can proceed with the pending contested divorce case.
His habits of visiting brothel can be mentioned as cruelty and added to your contested divorce case.
His bad habits can be highlighted in the child custody petition to show him in bad light to take advantage of his ill habits which may ruin the child's future, thus showcasing child's health as paramount, you can bring all his activities against you from the inception of marriage in order to hold your child back wit you.