Should I tell my older sister she has BPD

Backstory ... She is 50, I'm her 47 year old brother. Alcoholic parents, moved 13 times in 11 years, abusive, father has many disorders I believe. Everyone has cut ties with our parents including my father's siblings. We have anxiety disorders including OCD in the family, and autism.

I have self diagnosed OCPD, and have recently discovered my sister is a poster child for BPD and may have OCPD. Her spending like there is no tomorrow ways, my saving like crazy, and her general jealousy of me has my bringing anything to her of a critical nature seeming like a match to gunpowder. We don't trust each other, but merely function at the lowest form of adult siblings.

What bothers me a lot is - having recently discovered my issue (not easy given the nature of OCPD) - I wish to hell someone had told me years ago about something I could not see that I have been struggling with my whole life. While most of her attention towards me have been kicks/punches/shoves/verbal abuse/berating etc she has tried to help me on occasion, once even in adulthood so I think there may be hope. I'm getting advice not to bring this to her since she either does not know and won't accept it, does not know that I know, or does not want to talk about it, least of all with me. The way she berates her husband and kids (13,15) is revolting, and I'm afraid her constant screaming and cruelty will have her son's growing up with disorders themselves. I am committed to breaking the cycle with my young kids, but don't know what to do for her and her kids.

So, what should I do???

I think that a better approach is to ask your sister whether or not you can repair any strains in your relationship with her and find compromises to her irrational behavior which you may not approve of. The labeling of a diagnosis in many cases does not change how a person acts and is a little redundant sometimes. Telling someone they have a personality disorder such as borderline is just as effective as calling a person who drinks a lot an alcoholic. If someone tells you you have a problem and they aren't there to help you, then it will feel alienating and lonely.

The diagnosis may not matter in this case but the support is critical to helping your sister and nephew. It is hard to predict what effect a diagnosis will have on her, it could be positive or even negative. She could take it personally and it could alienate you from her. However, the effect that moral support such as taking her out to lunch and expressing how you feel it is inappropriate when she acts irrationally and hostile will most likely be positive. Assuming she is borderline, using "I feel this" statements rather than "you are this" statements will keep her hypersensitive emotions in check.

i agree with tayodore. no need to bring up diagnosis (especially if not confirmed by a professional). perhaps, what would be useful would be trying to get in touch with services, to sit down and realize that there are some issues. perhaps going together to look for some support without blaming things on each other and respective disorders (if they are there).

You are both likely right, and I intend to follow your advice as it mirror's that of my wife.

I also have a tendency to think for others, and to 'know better' than others. That would be my OCPD showing!

I truly appreciate the thoughtful responses.