Justin Bieber is ''torn up'' about his reckless behaviour as a teenager.

The 'Sorry' hitmaker penned an open letter earlier this week detailing how he'd used ''heavy drugs'', ''disrespected women'' and even considered suicide when his career started to take off and, although it was hard for him to share because he's ''embarrassed'' about his past, he found the process of writing it all down therapeutic.

A source told PEOPLE.com: ''He is torn up about his past. He feels a lot of guilt, because he knows he was a young, stupid kid. But what he's trying to do -- what we're trying to help him do -- is to channel that guilt in the right way.

''He needs to be open and honest about his past, because it's a way to heal. He wants to help other people learn from his mistakes. He feels like he made these mistakes for a reason, and that he can serve as an example of what not to do.''

The post took the 25-year-old pop star ''a long time to write'' because he wanted to make sure he did it all on his own in order to convey it in the ''right'' way.

The insider explained: ''No one told him to post that message.

''He decided to do it himself. It took him about a week. He did have a couple people look it over before he posted it.

''He's not embarrassed about sharing his heart. He's embarrassed at some of his behaviour in the past, but he's not embarrassed to talk about it if it will help people.''

Justin admitted that his issues began when he was 13 because his whole life - right down to his ''emotions'' and ''finances'' - was under scrutiny from the public.

He wrote: ''It's hard to get out of bed in the morning with the right attitude when you are overwhelmed with your life, your past, job, responsibilities, emotions, your family, finances, your relationships. Sometimes it can even get to the point where you don't even want to live anymore.

''... Humility comes with age. You hear these things as a young boy and you actually start believing it, Rationality comes with age and so does your decision making process. Everyone did everything for me so I never even learned the fundamentals of responsibility.

''By this point I was 18 with no skills in the real world, with millions of dollars and access to whatever I wanted. This is a very scary concept for anyone.

''By 20 I made every bad decision you could have thought and went from one of the most loved and adored people in the world to the most ridiculed, judged and hated person in the world (sic).''

By the time he turned 19 years old, Justin - who was dating Selena Gomez at the time - had started dabbling in illegal substances and had ''abused'' all of his relationships because he was ''resentful'' towards women.

He explained: ''I Became resentful, disrespectful to women, and angry. I became distant to everyone who loved me, and I was hiding behind, a shell of a person that i had become. I felt like i could never turn it around. (sic)''

Justin believes he's now going through the ''best season'' of his life after he married Hailey Baldwin last year because it's taught him how to be a ''good man.''

He concluded: ''Now i am navigating the best season of my life 'MARRIAGE' !! Which is an amazing crazy new responsibility. You learn patience, trust, commitment, kindness, humility and all of the things it looks like to be a good man. All this to say even when The odds are against you keep fighting (sic).''