Karrueche Tran is baring her body and soul in the current issue of Rolling Out magazine.

Chris Brown's 24-year-old ex, wearing nude undies, admits that her relationship with the singer "was very hard" ... especially involving the love triangle with Rihanna.

As for the controversial romance, Tran tells the mag:

    "The most challenging part about the attention was the negativity and the misconception from some people. People only see you in blogs and they think they know everything about your life. There are things that go public and everything that comes out is not the truth ... There was a lot of dysfunction and negativity. I just want to be happy."

The stunning model is now promoting her new clothing collection called The-Kill. Tran adds:

    "Chris started his fashion line and wanted to start his women's line. He asked me to be the head of the line. I brought along Ugo Mozie and MiMi Gazelle as my creative team. Once people see the collection, they will understand our vision. It's a unisex line and it's only black and white."

Interesting because until now, nothing in the Chris Brown/Karrueche Tran/Rihanna situation has been black and white!