Apologies; I hadn't read all the posts properly before I posted.
I understand your feelings better now; you are being overwhelmed by your husband's family, and it is not just your mother-in-law, it is also sisters- in-law and probably their cousins and their sisters and their aunts as well. Your husband has manipulated you into moving as close back home as he can get, by using his mother's serious, not necessarily terminal illness, and now he intends his family to play a large part in the upbringing of your, not their, child.
A poor way to behave.
You do have to take a firm stand over this and be very clear about what you want to do. It may be wise to hold on to your job, because you enjoy it, and it will give you some financial independence and a life away from this slightly suffocating family. Consider the possible options with your work first and if you decide to return, make sure that you organise the childcare first, then tell your husband your decision, and do not allow yourself to be be browbeaten.
It is up to you how much you choose to see your in-laws, and it would be kind to see them regularly; you may also be grateful for some assistance with child care later. But again, on your terms.
It doesn't sound as though it will be easy, but if you allow them to dominate the care of your child, you will be even more unhappy.