Your birth order coupled with poor parenting, often leads to family dynamics exactly as Rodney described and what you may also be experiencing. I believe long held resentment is likely behind your sister's behavior toward you, and it's possible that she may not be aware that this is an old pattern.
The only way I can see for her to break this pattern is for you to calmly point it out to her privately. You will always be her younger brother, but you ceased being the baby brother that she is angry with many years ago. Based on what you stated above, she tends to be more respectful of those who will not tolerate her bs. Don't be disappointed if your effort fails, however, because this a pattern of behavior that goes beyond your relationship with her.
I don't know enough about hubby to make anything other than a wild assed quess. He sounds a bit needy and insecure and he may be attempting to isolate your sister from her friends and family. He would ultimately have her to himself.
That's my 2 cents and I recommend you don't give it any more weight than that. You'll know if it rings true or not.
