It shouldn't have surprised me that Julie leaked the tape herself to push her career again. She was so desperate to get back in the public eye, she would have done anything. Did you see how desperate she was when she begged Lucy not to release the information?? God, she was really so desperate. But Lucy releases the story anyway - of course she does, because this way Holt will be free for her. At least I guess that's part of her motivation. Otherwise she would have gone for Julia's deal IMO.
How will Holt react? I think he'll break up with Julia, but blame Lucy for it. If he stayed with Julia after all... well, he's an idiot, maybe he does.