EVERYONE HELP answer about getting over my girlfriend?

Her and i broke up recently and she blocked me on facebook and told me not to call so she could get over me. Her parents seemed to have convinced her that she needs to live her life and not be tied down this young. I agree. Also her and i started getting into little arguments over stuff because I didn't treat her the way i used to and neither did she. But the facts still remain that it hurts severly how easy she can let me go after 3 years together. Her friends claim she is doing suprisingly well within just 5 days. My friend claims she was referencing a song about getting back together (on her wall post she mentions a song). She dropped off a few of my things by giving them to my friend. She brought some guy along with her and I don't know if she is trying to get me back by making me jealous, trying to feel better by making me jealous, or what? She brought him inside and introduced some guy to my friend. I know it sounds stupid and stuff but I am not a woman can someone explain this. Our breakup was mutual, shes 18 im 21......