Trust me, I know how it feels. I know exactly how it feels to cry in the shower so no one will hear you and waiting for everyone to fall asleep so you can fall apart. For everyting to hurt so bad you just want it all to end. I know exactly how it feels.
Trying to fill in someone else's shoes is futile. The person will at best be a shadow of the one who shoes they are trying to fill. It is best to have new shoes (their own) rather than live in the shadow of another