I am so sorry to hear that your sister is not supportive. My sister and I have never really been close. Every time she comes to visit she has nasty things to say. Honestly I just had to put up boundaries and try to avoid letting her hurt me.
Yes, she is your sister and always will be. That doesn't mean that she should be able to get away with everything. You should tell her that it is hurting you and that you wish she would be there for you through this process.
I am so sorry you are having to worry about this!