I hope your dh is taking some time off to spend with his mum, or at the very least taking her off sight-seeing at the weekends so that you can have some free time. I remember having several passionate whispered arguments in bed with dh on that very subject when mil visited us in Berlin.
Is there anything that she really doesn't like Hausfrau? You could make up a family routine that might give you some free time. For instance - if she doesn't like swimming you could say that you go always go swimming on Tuesday mornings (or whatever). Hopefully she will come down with a migraine or something and you can head out on your own with ds2.
BTW, when my mil was staying with us my dh took a "day off", on the morning of his day off he had to pop into the office first thing for "half an hour at the most", I went off to my German lessons and popped back home on my way to lunch with a friend and poor mil was still waiting for him to come home. He eventually came home at 3pm. I did feel a bit sorry for her, even though she's annoying.
Sympathy and support vibes from me too! We'll get together when it's all over and you can work through your trauma with me and coo over ds
Thanks for the mail btw! Will answer when not permanently feeding!