A letter Tupac wrote to Madonna is going up for auction. But that's not the only reason it is making headlines everywhere.

The letter published by TMZ reveals for the first time that the most revered rapper’s relationship with the Queen of Pop in the early 90s may have been more serious than we thought. And the reason for their breakup is more controversial than most of us anticipated.

Not much is known about their time together. There were rumors about the two dating in the 90s, but it wasn’t until a 2015 Howard Stern interview that Madonna confirmed their relationship. Tupac’s brother, Mopreme Shakur, also told Vlad TV that Madonna and Tupac "were a thing for a minute."

"She gave me a note to give to him; I was just happy she was giving him a note. Everybody was there. I went over and gave it to him. He was about the business and then they linked up. I would take him to her house and s–t when we got back to L.A."

The prison letter that is being auctioned off sheds some light on the unlikely pair’s relationship and their break up. TMZ has redacted four parts of the letter but here's what we've gathered from it so far.

Tupac begins the letter by apologizing for not having been a good friend to Madonna.

"I've waited a long time 2 finally write this mainly because I was struggling to find all the answers that I wouldn't leave any unanswered questions.

First and foremost, I must apologize to you because like you said I haven't been the kind of friends I know I am capable of being."

Tupac then confesses to Madonna that he broke up with her because she is white.

"Can u understand that? For you to be seen with a black man wouldn't in any way jeopardize your career. If anything it would make you seem that much more open & exciting.

But for me at least in my previous perception I felt due to my 'image' I would be letting down half of the people who made me what I thought I was.

I never meant to hurt you."

He goes on to write about an interview Madonna gave that hurt him.

"An interview where you said I'm off to rehabilitate all the rappers & basketball players, or something to that effect.

Those words cut me deep seeing how I had never known you to be with any rappers besides myself.

It was at this moment out of hurt & a natural instinct to strike back and defend my heart & ego that I said a lot of things."

Tupac also shares that he has grown and no longer feels the pressure to live up to an image.

"Can you feel me? In the time since, as u can see, I have grown both spiritually and mentally.

It no longer matters how I'm perceived.

Please understand my previous position as that of a young man with limited experience with an extremely famous sex symbol."

The rapper then extends an olive branch writing:

"I offer my friendship once again this time my stronger & focused.

If you are still interested I would like to further discuss this with you but some of it couldn't wait.

I felt compelled to tell you…just in case anything happened 2 me."

Tupac also issues a warning to Madonna.

"Please be careful Madonna. Everyone is not as honorable as they seem there are those whose hearts bleed with envy & evil. They would not hesitate to do you harm! Let my 6 bullets be proof of that!"

He ends the letter asking her to visit him in prison.

"I don't know how you feel about visiting me but if you could find it in your heart I would love to speak face to face with you.
It's funny but this experience has taught me to not take time 4 granted."

Tupac was fatally shot three years later.

This letter, written January 15, 1995, at 4:30 am, will be auctioned off between July 19-28. According to TMZ, the starting bid is $100,000. Tupac's last letter to a Death Row Records publicist went for more than $170,000.