It hurts to be told this. It happened to me after a nine year relationship were I was told the same out of the blue and left me heart broken. There is one piece of advice I can give you. Do not contact her ever again, for any reason, ever. Not holidays, birthdays or anything else. If she has fallen out of love with you she is the one that needs to miss you enough to contact you. That may or may not happen. In my experience it does happen but not for a long time; months or years, by which time you'll have moved on with your life.
Start to work on yourself, your fitness, sports, languages, musical instruments etc. I challenge you to learn Spanish and French and learn to play guitar. These will help you establish an identity outside of her and the relationship. There is a great future for you without her, believe me.