What is the ruling of revealing the sin and transgression of someone close to you to pious individuals who can make du'a for the reformation of said person? Does this constitute to exposing a sin in public and backbiting and is the one revealing it sinful?
In general, discussing your sins is haram as it was narrated that Abu Hurayrah said:
I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “All of my ummah will be fine except those who commit sin openly, and it is part of committing sin openly for a man to do something at night, then in the morning when his Lord has concealed him he says: O So and so, I did such and such last night, when his Lord had concealed him all night, but in the morning he discloses that which Allah had concealed for him.”
Unless there is a legitimate excuse for you to reveal your sins such as to get a fatwa, to get health advice from a professional such as if you were suffering from alcohol addiction and other harmful things than it would be ok, however anything else there isn't a need and wouldn't be permissible rather you should tell your close friend to make dua for you to better yourself and make Allah guide you to the straight path and also make dua for yourself, rather than disclosing your sin.