Will he leave me for his ex-girlfriend?

Ive been talking to this guy for about 4 weeks or more and we've gone pretty serious. His ex girlfriend wants him back and she hurt him pretty bad so he wanted someone to treat him right which would be me. She kept calling him on his phone begging and crying to have him back but she treated him like dirt. They dated for about a year and a half But he was tired of gettting hurt over and over again. But resently he got grounded and got his cell phone taken away from him and i have no way of contacting him because his ex girlfriend keeps going on to his facebook and checking his messages between us and deletes them and claims he told her to because he wants nothing to do with me and that im just a rebound but many of his friends say that he is a very sweet guy and he's not like that to say such things.. But his ex also claims that he called her and told her he wanted her back and that she was the only one for him and that he loved her and other things... But idk what to do .. im tired of woundering if its me or her because i was raised not to fight for any man. And im done with her gloating im my face saying " hes mine and you cant break something up that was longer than a year" and so forth. Could someone please help me i wish this would all go away..:(