Jeez - with sisters like that, who needs enemies???????
Seriously - I don't care how much of that was "true" or not - how completely inappropriate was your sister???? Let me ask you this - why is she jealous of you? Because i suspect some jealousy under her eagerness to tear you down at the worst time of your life.
Sure, you could have been a better wife - who couldn't? And you probably have issues you should work on. But NOTHING you did justifies what your H has done here - okay????
I'd stay away from this sister for a while - she's not a healthy relationship for you at the moment.
