Sharon Osbourne: Lady Gaga is a bully

Mess with Kelly Osbourne and you get the horns Sharon Osbourne.

Mama Osbourne shot back at Lady Gaga soon after the pop star posted an open letter to Kelly on her website Thursday, accusing her of being a bully on E!'s "Fashion Police."

"I am responding to your open letter to my daughter Kelly, and I am perplexed as to why you would go public with an open letter," Sharon posted on her Facebook page.

"Regarding this current situation," Sharon continues, "Kelly didn't contact you, I was the one that contacted your manager ... I reached out to him as Kelly's manager and mother to ask him if you could address your 'little monster' fans and stop them from writing libelous, slanderous and vile comments about my family, including death threats to Kelly," which she received after making comments about Gaga's weight on "Fashion Police."

In response to Gaga's note that Kelly has "chosen a less compassionate path" in life, working on "Fashion Police," Sharon says: "I must say your opinions on what is politically correct and acceptable totally differ from mine, but that is what makes the world so interesting ... we are all different."

Sharon later calls Gaga a "hypocrite and an attention seeker," noting, "it would have been much more dignified of you to do this privately. I am calling you a bully because you have 32 million followers hanging on your every word and you are criticizing Kelly in your open letter. Are you so desperate that you needed to make this public?"

Kelly chimed in on Thursday evening via Twitter, writing, "I hope you guys realize that I don't care about any of this bulls-! I know who I am I don't need anyone to tell me!... love to all xoxo"