I am asking because it sounds like it could cause you more problems. If you think your child and her could and would have a healthy relationship then it is something to consider. But if you think it would just cause more problems or endanger you and your child's safety I would think twice. I don't know her so I can't say either way. She could be very accepting or she could be hurtful and reject your child. Either way you need to weigh things out and decide what is best for you and your child. It isn't easy dealing with these situations especially when children are involved but it is your job to keep him safe and keep yourself safe so that you can take care of him.
I can tell you from personal experience that not all grandmothers care or want to even be involved with their grandchildren. It can be very hurtful for the child and the mother. It is angering when someone who should love them rejects them, being a mother and watching them be rejected and hurt is hard to take. But you can't force a relationship if they don't want it. Just be careful and do what is best for your son, not what you think is best for her.
I really hope it all works out for you. Please give updates I will be praying for you and your son. Take care