The book "get me out of here" by rachel reiland is great, if your sister is interested in knowing more about what the internal experiences are like.

As your therapy helps you, it may also help your relationship with your sister.

I think you are brave. I would not attempt to try to explain to my siblings, because I think it would just lead to more misunderstandings and inability to truly 'get it'.
But I wish you the best of luck!