Dont get me wrong Im not an inlaw fan, however...Once a week, assuming they only stay for a few hours, doesn't sound too bad? -or is there a more specific reason why your inlaws are unbearable?
I agree with pp: they probably already cared to some degree, a bubba coming just spurred them to pull their finger out.
I can see how your FIL visiting every day in the hospital would have been a pain if you were breastfeeding, however it was up to you and hubby to set the boundaries there.
It seems like a bit of an over reaction OP: are there other underlying issues causing your stress? Do you need more of a hand around the house (from hubby etc) new bubs can be overwhelming.