YTA Your husband is right. You did go behind his back and betray his trust, and worse, with regards to the well-being of your child. How will he trust you after this?

As for your mother, that's horrible advice she gave you, and the sort that will destroy your marriage. Women are not powerless any more, and so manipulation and deceit are horrible leftovers from an awful system that no longer have a place in a healthy relationship today. Also, we know better today about respecting babies'/children's rights and safety.

Is this the person you want to be, OP? Someone who cannot be trusted to honour her partner's role and wishes, who cannot be trusted with her child's well-being and safety, and who goes behind her partner's back to get her own way?