GAGA’S EX-ASSISTANT TELLS ALL!

Lady Gaga’s past is coming back to haunt her. The singer’s former assistant Jennifer O’neill (inset) is about to release her highly anticipated tell-all, Fame Monster, and it promises to show a side of Gaga that we’ve never seen before. “Jennifer’s going to reveal all the dirty secrets about Gaga’s sex life, hard partying and how she treats people, especially the men in her life,” says a source, adding that the singer, 30, tried hard to get Jennifer — who sued Gaga in 2011 for $400,000 in unpaid wages — to sign a nondisclosure agreement but failed. “Jennifer wants the world to know the real Gaga, and she isn’t holding back.”