There are always two sides to every story ( except in the case of MH) it sounds as though this is their first grandchild. They are far too over involved, probably through excitement.
There is no doubt that they are wearing you down, but on the other hand they are NOT mind readers either.
I have to admit that I was so incredibly excited when my first GC was born that I went bananas. I bought too much stuff and fell deeply in love....BUT the difference was that it was a daughter’s baby.
So I was sat down and ‘told’ Stop buying and stop making demands. . I listened and stopped. I did feel a bit hurt as I am only human. No one likes being told off, after all.
You can cut your PILs out of your life for what they are feeling and doing to annoy you, and they will never know WHY unless you tell them. Surely it’s much better and humane to try and tell them as kindly as possible, that they are overwhelming you ?
The best and most successful marriages are where all family members try and get on.
The knives are usually out for MiLs on Mumsnet and even when those of us who are MiLs, try and relate our experiences, purely in order to save a miserable situation escalating, our advice is often treated in a derisory manner.
The relationship between inlaws is rather unique as you are inherited, rather than a blood relative. You have to try and get on and love one another, and it’s not easy.
You could engage your DH to tell his Parents to stop, but unless they are totally stupid, they will know the directive comes from you.
The outcomes from 2nd hand conversations are not so satisfactory. Hard as might seem, it is better for you to speak to them.
Practice beforehand saying your piece in a non confrontational and assertive manner, leaving them with some dignity if you can.
Remember that there is absolutely nothing to be gained by them in trying to hurt you. Why would they? I personally would do anything to get on with my SIl s and DILs but we need some dialogue, surely.
Otherwise we have only have sulking and cold shouldering as a alternative.
My username isn’t grammatically correct ( I know but I am not absolutely sure how to change it) just in case the Grammar Police feel like commenting.
Best of luck OP, as dealing with in laws successfully, can be fraught. Go for ‘the talk’ option.
If they continue afterwards, then they are a ‘ nightmare’ and deserve all they get.