((((((((((((((((((((((((NN))))))))))))))))))))))))))
You sound like a wonderful brother, and wise too.
I hope that once your sis has the baby, her hormones will quiet down a bit, and maybe her marriage will get better and life won't seem like such a struggle for her.
I understand how her hold on you can make you angry at times and frustrated. I'm sure you do your best to keep calm and try to remember it's because she loves you. These things will hopefully work themselves out with love and patience and understanding. Even though I know at times its so hard to be that way.
I wish you all well
Hugssss
J