How I Wish She Is Like My Sister's Childhood Friend Or Good Friend...

I feel so envy whenever I see my sister talking on the phone with her childhood friend, or talking to her good friend which always visit her at her place or take us out for lunch. I wish she was like my sister's good friends. They share almost everything that even I am her own sister never know what my own sister is facing.. Sometimes I just wish I know what my sister's facing or feeling, wish she tells me like she tells her friends. But now I wish I could hear from my very own good friend her problems and secrets. Wishing we didn't need boundaries in between us.
At times I wish I could tell her everything and she will do the same to me but since so many secrets in our life I don't expect anything at all and I respect her and she will be able to keep whatever secrets she has to her own and I will keep mine to myself too. Things aren't important I will share with her but things that hurts me or killing me let those fill my lungs and souls.
How I wish I wouldn't feel envy or jealous how my sister friends surround her. If only my life isn't limited in anyway. God knows how it feels.
How come it's so easy to feel her sadness and whenever she is down...... How come I can sense it? You got them babe, I got only you but I always remember I have many forbidden things in my life not only with you or them but in my family too.