But the MTV reality star, 25, has a message for fans.
"Please stop bashing Luke," she Twittered earlier this week. "I don't hate him so why should you? We are still best friends, just not dating, so enough now."
An Osbourne pal tells Us Weekly "Kelly was blindsided" when she learned her beau of two years had strayed. "Everyone thought Luke was a real sweetheart. [Her mother] Sharon wanted to give him a piece of her mind, but Kelly begged her not to. She wants a clean break and to move forward."