**Adding this: I certainly HOPE that the others (your son, your brother, her aunts and uncles) KNOW that you are not the "bad guy" here??? Otherwise, you will have a posse of people, against you too. It seems she is trying to obliterate all respect, toward you, among everyone.
Try documenting things... ya never know, it may come in handy... for you as the Spouse of your Husband.
She is reacting that way, because her Dad is very sick, had a stroke, has been near death... and she can't handle it. It is like she had a nervous breakdown.... she cannot think straight... she is "blaming" you for his condition... thus she is hateful toward you. You are her target, for her inability to handle her emotions, nor come to terms with her Dad's condition...
No its not right. But she is displaying an emotional breakdown.
She is excluding and blaming you.
Can't she just see her Dad.... alone or with her twins... without you there?
Or, she has to realize, that you NEED to be there because of your Husband's FRAIL condition... and you are like his "Nurse." Caring for him daily. She HAS to realize, that you are taking care of her Dad. She will not admit that... she has to "blame" someone for her Dad's illness.
Your Husband, needs to see his Grandchildren... especially being in his condition...
SHE cannot just place her Dad in an institution... your are his Spouse. AND... many elderly, actually do worse in an Institution, because they want to be near family. Or a hospice is an alternative.
Also, do you have an "Advanced Directive" for your Husband? You both need this... since he is ill. Get all your paperwork in order... now while he is still with you. *AND... make sure all the wills/estate plans/legal things/beneficiary designations/Insurance etc. are IN PLACE... before your Husband gets sicker. Otherwise, your SD will cause trouble, for you. You are his WIFE... and you need to be sure you are taken care of, should he pass on.
Yet, your SD does not want to be "near him" because he acts all nervous... well, he is sick. Very sick. And she CANNOT cope. She thinks in her little mind, that sending him to an "institution" will then solve HER problem of having to see him that way. She is avoiding the problem... HER problem of the inability to handle this.
*My Dad, was ill like that. He eventually passed on. During my Dad's illnesses.. my sibling, was very wicked and mean and hostile to me and my Husband. She would even have "discussions" with my Dad talking stink about me/my Husband to him, trying to brainwash him against us. My Dad knew, he was cognizant... he told me. He told her off. AFTER he died... my sister, only then, regretted and then behaved nicer. Some people... only learn, when it is too late. Because they are not capable of taking the higher road.
all the best,
Susan