My Sister Is Not Being Treated For Her Mental Illness

My sister is untreated for her mental illness. Now she's lashing out at everyone, sending emails telling us that we "ruined" her life and that we are unsupportive of her extremely bad decisions, like dating men 20 years younger than she is. She is paranoid and making up lies about other family members, saying that our Sister in Law is trying to kill off our Mom and put our Dad in a home to steal the inheritance. I feel sad that she isn't getting help for her obvious mental illness. She's currently living overseas, so we can't have an intervention.

Now we have another sister who is going through a messy divorce that's been a long time coming, and this insane sister is sending her horrible emails telling her not to get divorced, that she is ruining her life and making a big mistake. The rest of the family is supportive of the divorce, as he is verbally abusive and has cheated on her and become very mean and paranoid. Now come to find out that the insane sister has tried to contact the soon to be ex husband. Even he thinks that she's crazy and has told our sister not to trust the crazy sister because she's emailing him with strange things.

She has a lot of problems with jealousy. Last year I got married to my long term boyfriend, and the insane sister snapped and couldn't handle it and tried to ruin my wedding by creating drama. Now she's obsessed with me being married and keeps saying, "Now that you're married you're the favorite one and I'm the black sheep." She's way too old to be behaving this way. We should all be happy for each other at this point.

I have tried to tell her to please get treatment, but that did not go over well. Now I have to walk away. But it makes me sad to give up on a family member.