Why is it so hard for me but so easy for her?:/ please help......?

me and my girlfriend just broke up. i was in love. deep in love and she said she was to. but i cant move on. i miss her. i cant sleep because of this. its killing me. but it seems like its not affecting her. i saw her the other day for the first time since the break up. i coulnt stop looking at her but she couldnt stop looking away:/ she says shes getting happier without me but my life gets darker and darker everyday were apart. it feels like everything is closing in on me. the life i oncce knew seems like its crumbling on top of me i dont know how to handle this. she was my first love and i still love her as much as i did when i said it to her for the first time it seems like all i ever do now is pray and cry. what can i do? how can i deal with this i need help................