It's the dilemma we all face, there are no easy answers. It's a shame your family is so brainwashed they cannot see the futility and cruelty of their actions, but that is the reality of the situation.
Some feel the effort to go back and live a lie is worth it to maintain family bonds , others do not, it depends on your feelings about your family and the toll it would take to live a life you don't want. My choice was easy, my parents are gone, my children are not in the religion and I value living my life on my own terms more than the association with my two JW siblings, as much as I care for them. But that's me, your milage may differ.
My suggestion: If you do go back, make it clear to your mother that you are doing this just for them, but that it is going to take a toll on you to live something you don't believe in, she should know she is hurting you. If you don't go back, write her a letter and tell her how much her stance is hurting you and your child. And don't let her have access to that child, she doesn't get to reject you and see her granddaughter. Find a nice older woman to hire as a babysitter so your daughter gets the love of an adoptive grandma. If I lived in your city I would do it for free. Not to brag, but my "itsy bitsy spider" skills are top notch.
Only you can decide what is right for you.
Lisa 🌹