How does joint property where I share loan EMI get split after divorce

As you stated that, there has been physical violence also.
We would suggest that you should initially 

1. file a complaint to the women cell regarding the physical violence.

2. file a complaint to the police under section 498a of the indian penal code.

3. file a complaint to the police under the Protection of Women from Domestic Violence Act

Now regarding divorce,

Assuming you are Hinuds,

You can file for divorce under section 13 of the Hindu Marriage act.

In your case, the ground for divorce falls under section 13(1)(ia) which deals with cruelty.

Now regarding your child who is 4yrs old it is laid down by The Hindu Minority and Guardianship Act, 1956 that custody of a child upon the age of five should ordinarily be with the mother.

You can claim for maintenance under section 125 of Cr.P.C. as well as section 24 of the Hindu marriage act and the court after considering your case will divide the property and loan as it thinks best for both your husband and you.

You can otherwise go for a divorce by mutual consent under Section 13B of the Hindu Marriage Act.

This would help you divide your and your husband's share in the property and loan in an amicable manner under the terms of your divorce. The terms of your child's custody can also be drafted in the same if your husband also consents for a mutual consent divorce.