What I feel in the heart is only aching... Of not even knowing my own sister Brenda

I am not okay. I don't what or how long this not okay is going to be.
One thing I know of everything I can't put my hand on is this - My Sister is gone.
My Sister that I always took things out on, picked on her, when we were kids.
From being under 12 until 4 years ago I never knew her, knew where she was, what she was doing, how she was doing...
Nor be there to support her so she wasn't alone within herself.
Knowing what this feeling is, what this pain is - at least I know what it is. It's my pain for not knowing Brenda.

The other confusion in my brain, life, heart, emotions, interactions - I don't know how I feel about them, because I really don't what they are...

What is good is that I know at least one thing - I feel this emotion due to the loss of Brenda.