My 81-year-old sister is being emotionally abused by her husband. How can I help her?

Happyjack
Just mulling this over with you ...
There is a common answer we give on this site when someone shows changes in behavior. It's to check her for a UTI (urinary tract infection). This infection is easy to check. The patient doesn't always realize they have it because they don't always have recognizable symptoms but it can cause a person to behave as if they have dementia. An antibiotic is all that's necessary to cure it. Left untreated it can cause severe problems. If she has never had one she might not know to ask for a check and many drs seem to not know to run this simple pee test. She could run by an urgent care for the test or even pick up a kit at the drug store. If the test is positive she could call the dr for an antibiotic.
Medicare will pay for therapy. Encourage your sister to see a therapist to discuss her problems.
Also encourage her to exercise. Ask her to go for walks with you. Of course the drinking to excess will make everything worse. It's wonderful that you want to help your sister. We often advise caretakers to slip notes to their elders doctors giving them a heads up on issues the elder won't discuss on their own. My sister has asked me to leave her drs office before because I was telling too much family info. We laughed about it but I knew she was serious about me butting out. It's a hard call. With the conditions you describe it sounds like she needs to toughen up in order to keep her husband from running her over. Living with that kind of stress will take it's toll. If her dr has changed her meds the alcohol might not be appropriate with some of the new meds. I think I would tell her that I had noticed a change recently and that I was concerned. By her comments she has noticed a change too. If husband has always been a jerk you would think she'd be used to it, so tell her you are concerned it might be something more. My friend and I decided that we would tell the other when we noticed changes that might need to be checked out. Someone to watch each other's back. Perhaps that's something you could consider. It might be awkward to get the conversation started but once you got going it would get easier. Tell her you want her to win, not BIL. You might also talk to her about giving you or one of her kids her POA.
If BIL doesn't have her best interest he shouldn't have the POA. She doesn't have to broadcast it, just get it taken care of.
She's lucky to have you in her life.

This is her and his second marriage. My sister has 3 adult children and they are somewhat supportive but have so many of their own problems it's difficult for them to be supportive. She stays with him because a lawyer told her years ago that it was too late for her to leave. There is no money and no one that she could live with. Her daughter lives with her, one son rents a room, and the other one lives in an RV. They have been married around 40 years. No children together. My BIL states that "the last one to die is the winner"! He is manipulative, cunning, smart, and controlling. She has no back bone and everyone knows that so they take advantage of her. I really don't think she would ever leave him as she likes the "trappings" and has always been materialistic. My main question is if I should contact her PMD and let her know of the negative changes in her behavior. I am the only person my sister trusts and I do not want to betray her. Her doctor has been trying to get my sister's meds sorted out. I don't know if there has been a change in her meds that has resulted (partially anyway) in this marked behavior change. Guess it could be the start of dementia or just an accumulation of so much stress for so very long that she just can't handle things anymore.

Why do you think she stays with him? Have they been married long? Do they have children together? Do the children offer any emotional support? Tell us more about her situation. I know it must be awful to witness.

Happyjack, I am moving your question back to the front of the line. Hopefully someone familiar with this type of situation can help out.