Has your H done anything at all to call Mil on her behaviour towards you?
I think you are right in that your Mil's behaviour IS about control; she wants her son to herself, and your place in his life is an irritation to her. Maybe that's the cause of her behaviour-she's lashing out at you in frustration. But it's spiteful, destructive behaviour. And being able to explain behaviour doesn't make it right.
I hope you don't mind me saying this-and I may have grabbed the wrong end of the stick on this-but there does seem to be a pattern in your parents' and your own behaviour. Your parents have behaved impeccably (from what you say) and so have you. They have tolerated poor behaviour from your husband, as have you. You have suffered, both physically and mentally, while your h has lost nothing, and is carrying on as before. No flies on him, as we used to say in the office when some lazy b..rd got away with something again.
You sound like such a kind, sensitive, thoughtful person...what I'm trying to say a bit cack-handedly is that maybe you've taken too much of the blame for others' poor behaviour, whilst they've not only got away with it, but continue to behave badly towards you.
I think it's time to step away. For the sake of your mental and physical well-being.