07/19/2012 02:34 pm ET

Ray J Mocks Kim Kardashian About Sex Tape Past

Is Ray J really in any position to be making fun of Kim Kardashian?

On Wednesday, Kim's ex-boyfriend and sex tape co-star decided to take a shot at the reality star by laughing at a series of uplifting tweets.

"U wouldn't be who u are today, u wouldn't have the depth, maturity, & the insight were it not for those challenges that forced u to grow," Kim wrote on Wednesday night, adding: "Keep your life in a positive perspective. We are not defined by our pasts."

Kim, of course, has made some mistakes in her past, namely her 72-day marriage to Kris Humphries and the sex tape she made with Ray J way back in 2003.

Her ex took the opportunity to mock the 31-year-old star, replying to her tweet with a simple "LOL."

Kim kept it classy and hasn't responded to Ray J's tweet -- just as her current beau, Kanye West, ignored Kris Humphries after he mocked him on Twitter earlier this week.

This isn't the first time Ray J has taken a shot at Kim. In his book, "Death of a Cheating Man: What Every Woman Must Know About Men Who Stray," he hinted that Kim cheated on her first husband, Damon Thomas, with him, and wrote that their relationship was mostly a sexual one:

"There was more to our relationship, but the majority of it was about our wild and extreme sexual chemistry. She was a straight freak who was down to do whatever, whenever and that seriously hypnotized me," he wrote.