Demi Lovato is said to be 'gunning' for Twilight star Ashley Greene after she supposedly confronted the actress over her relationship with her ex-boyfriend, Jonas Brothers star 'drove her crazy.'
A source told showbizspy.com: "Having Ashley around all the time drove Demi crazy. At one of the shows Demi got in Ashley’s face and went nuts. She had tantrums over the fact that she couldn’t win Joe back.”
Previous reports have also claimed that Joe 'used' Demi to raise the profile of their movie Camp Rock 2, which is said to contributed to Lovato's health issues.
An insider added to the celebrity gossip website: "Demi had no idea that Joe was just using her and when she found out that the whole relationship was just for show she had a mental breakdown over everything."
“She felt everything was a big lie. When Joe and his father told her the truth, she couldn’t deal with anything anymore."

They continued: “She totally lost it, and nothing was ever the same after that. She didn’t know who to trust or what was real anymore. In all honesty, she loved Joe, and to find out it was all fake, destroyed her."

“She immediately started blaming herself after they split, and wanted to change everything. She tried to move on. She started seeing other guys to distract her. But being stuck on tour with Joe and his new girlfriend did her in as we see now… All her feelings just exploded at once.”

Meanwhile, Demi's stint in rehab has reportedly caused bosses at Disney to make changes to her show, Sonny With A Chance.

GossipCop has claimed that the programme will now focus on the show within a show, So Random! until Demi makes a full recovery.

A network spokesperson stated the change will allow Demi: "the time she needs to get well, without distraction or pressure. Again, we extend our ongoing support to Demi and her family as she works to overcome personal issues.”