Hello Butterfly1250!

I am glad you found us! You really have a lot going on between your sister and your sister-in-law! The drama can really be frustrating and I can understand your feelings of anger toward the disorder.
You have found a great place to share your experiences and feelings. One of the most frustrating things for me has been trying to explain BPD to other people! But here it is different, here you will find people that actually get it. it has been so helpful to me, and I know it will be for you too.
Are you older or younger than your sister? I am assuming you have a brother as well, any other siblings?
I think it is great you are in therapy. I Feel the best thing we can do is take care of ourselves first.
I encourage you to read and post on the
[L5] Coping and Healing from a BPD Parent, Sibling, or Inlaw board. There are many experienced members who can help you improving your handling of relationships impacted by your BPD relative, and also help you continue to care for yourself. The validation, information, and support will give you strength on your journey.
Bananas