Ah! I can understand what you must be going through. Your heart sinks whenever you think of leaving the baby, and no matter, that be your husband or parents. But, I think, do not worry. Your mom is his 'two times a mom', and she is going to take care of him with more love than probably did your time. I know it would be difficult initially, but when it is your mom then I think you should let all your worries rest. Go ahead and all the best.
Whatever your mum does, don't be too upset. What u dun see cant hurt u. Ignore all the wrong things that u might be upset with yr mum. :) she probably will claim she knows better than u because she's your mum and u ended up fine.