Thank you for your enquiry.
No matter what the difficulties are between you and your husband, a child should not be denied access to any of its parents. If there is a genuine relationship between a parent and his/her child, the Immigration Rules shouldn't be used as a means to facilitate a denial of access. You should be careful in taking your child out of the UK jurisdiction without consent from the other parent with parental responsibility. There are complex issues with regard to child abduction and family law for which I am not able to give you support.
But with regard to the immigration element for which I am able to provide support, under the Immigration Rules a parent who is not in a genuine and subsisting relationship with the other parent, can apply to remain in the UK to have access his/her British child.
In terms of your husband's current status as a spouse, if your relationship no longer exist then it is unlikely that your husband is able to remain in the UK as your spouse.
If your husband already had a spousal visa in the UK and before the birth of your child, I am unsure what you mean by "it is obvious that he only had a child with me to obtain a visa"