So you are lucky to have parental support.
Nah. Not these parents. You shouldn't be grateful for feeling like shit, heat or not.
My parents are extraordinarily controlling (under the guise of being overprotective). You're actually better off coping alone than putting up with their crap as well. And from the little I've heard, I really don't think it will get any better after baby is here.
I had to live, at various times, with narcissistic controlling parents, when DS1 was 6 months old. It was absolute hell. I'd have been better off homeless with DS (obviously not, but you get my point).
They are emotional vampires, and they suck all the joy out of everything.
This should be such a wonderful time for you! You are getting ready to have your first baby!
My friend was petrified of hospitals, so I was there for her (single, father had left, no family apart from her mum) and I was there talking to her, keeping her distracted, helping her cope (she suffered with panic attacks).
What I'm saying is.....where is your emotional support??
Pregnancy is very very hard.
I was like you. Hating upsetting anyone, hated confrontation, didn't want to upset family, didn't want to tell DH what they were saying about him (which is worse keeping it all to yourself!) - but I'd be looking very lovingly at that B&B right now, and indulging in mutiples baths, and reading and relaxing before your world is turned upside down - in a nice way 
I'd say to them - because you're a fucking nightmare to live with and you're not helping me at my time of need! But if you want something diplomatic, say you are desperately worried about your father, and how much pressure this is putting on him, and you would rather not be a burden on him and allow him to take care of your mother without the added pressure of taking care of you too.
Then I would change my name and disappear 