Once upon a friend time, Lady Gaga and Perez Hilton were buddies. But Lady Gaga recently went all KANYE ON TWITTER at Perez Hilton and alleged that he moved into her building to stalk her.

Lady Gaga wasn't home at the time, but she had a panic attack. She tweeted to a fan to take a picture of the famous blogger (and now her enemy) who was spotted in her building, and called security to escort Perez (real name Mario Lavandeira) from her apartment building.

Gaga and Perez used to be friends when she first started out, but they had a falling out in recent years, when Perez constantly ran negative stories of her on his blog. Most recently, she complained that he sent her nasty texts when she hurt her hip and was confined to a wheelchair.