My sister and I are very close.  She has BPD that is pretty much untreated. Yet she and I have always managed to have a good relationship because I’ve been able to work around her and know the “right way” to talk to her. But right now, I don’t know how to deal with this one. 

The last few months she has been closed off to me more than she’s ever been. I thought it was odd but since nothing was boiling I thought it was ok. 

Now I find out she’s been cheating on her husband and is currently finding ways to justify the boyfriend. It’s heartbreaking. Her husband is amazing and is desperately wanting her to end it with the boyfriend and commit to the marriage and do marriage counselling etc. 

My problem is I am so angry with my sister. So angry. I want to yell at her and text her all my raw feelings. But of course, I can’t because that won’t improve things. And so instead, I am silent. 

How do I manage this one? Knowing that I am not on her side and want her to go back to her husband?