Hi, I'd like to help you with your question.
From your description, it sounds like your sister has more than OCPD. She may have another personality disorder or she was misdiagnosed.
You describe your sister as yelling, swearing and blaming you when you have done nothing wrong. What you are describing is someone with Borderline personality disorder. Although I cannot say for sure your sister has Borderline Personality disorder, her symptoms do fit.
There are two ways you can cope with your sister. One, you can lower your expectations. Talking with your sister is going to be like walking through a mine field. Keep in mind that anything you do can set her off. She does not realize anything she is doing is bothering other people. People with personality disorders rarely have insight or see anything outside of their own experience. So yelling at you and swearing is justifiable behavior because in her mind because she feels you did something to make her act that way. Try to keep your emotions out of your dealings with her. People with personality disorders often provoke emotional reacts in others because their behavior is so offensive and hurtful. Training yourself to not react and to remain neutral can help. Develop a few non emotional responses you can provide to just about anything she says to you, especially when she tries to provoke you. "I'm sorry you feel that way" is a good response to just about any comment. It leaves your feelings out of it, negates a reaction and may keep her from feeling offended.If you feel you still do not want to deal with her at all, then it is alright for you to not talk with her. It is hard to ignore your own sister, but when her behavior is so hurtful and difficult to cope with, it leaves you little choice. Protecting yourself is the most important thing when dealing with someone with a personality disorder.You can also learn more about personality disorders to help you find more ways to cope with your sister. Here are some resources that will help:
Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder-Paul Mason MS
The more you can learn about personality disorders, the better equipped you will be to deal with your sister.
I hope this has helped you,Kate