She said that my brother didn’t experience the same things as I did.

For years I thought that even if my twin sister didn't have exactly the same terrible things happen to her that happened to me, she would be able to understand because she also grew up in the same house. Well, now our mother is dying and a lot of stuff about her neglecting me is coming up (and fueling a lot of anger) and it turns out that my sister had a very, very different experience (this is the week where I learned the terms 'scapegoat' and 'golden child') growing up. While this is painful to realize, I also understand that it in no way invalidates what I experienced.

It's good that you're in therapy; that will greatly help things, I think.