Oh, I'm really sorry to hear that. Have some virtual hugs from a stranger.
I had a similar experience at the beginning of the year - slightly shorter relationship, but I was very much besotted and he, without warning, broke it off.
All I can say is that you'll spend a lot of time in the shaken, crying, not-eating stage when you keep remembering the raw pain of the sudden and unexpected ending of something you were heavily emotionally invested in.
Then you'll start to think you can move on, but it'll be in a numb sort of way, in which everything makes you think of him and you just want to see him, to hear his voice, for him to tell you it'll be ok, and that he's realised he was wrong. This bit is actually far worse than the initial shock, as it makes you feel really desperate and pathetic. It passes, slower than you want it to, but it does pass.
Eventually you'll start to realise that there is a world outside that relationship. That perhaps he wasn't the one for you. That although you still miss him dearly, you begin to think that you actually might be able to make it without him.
That's as far as I've got. I believe future steps include the whole moving on and finding a newer, better manshape, but right now that thought is difficult for me to comprehend, so I don't expect you to be anywhere near ready for it.
What you need is support, and understanding. Take advantage of all support offered to you, in RL and online - I'll bet there are dozens of ladies here who have had their hearts broken (or merely bruised - I refuse to accept that he broke mine, although it felt like it at the time) and who have survived to tell the tale. Your wound is fresh and needs time to heal, but I assure you that it will be ok.