Please accept my ((((((((((((((hugs)))))))))))))). I know how hard it is to be alone and feel so alone. And certain holidays such as New Years Eve make it even harder.
But what you need to realize now is that all the feelings that you are having are actual normal and are to be expected. You obviously care for your former girlfriend quite a lot and it sounds like this has all been a shock for you. But as hard and lousy as this all is you still need to take care of yourself right now. And coming here to this board is a great step. Just the other night I had posted with my own thoughts and hearing back from others lets you know that people actually do care about you and are here to unconditionally help you. Keep reaching out --it will do you some good.
Also, don't be so hard on yourself right now. It may or may not take a little bit to get back on your feet again and feel like yourself. Try doing some things for yourself right now like journaling all your feelings into a notebook, going to see any movies that you have not seen (I have found that going by yourself is not so bad because you have time to reason things out on your own going back and forth and then you have some brief time to escape it all during the movie.) Things like this can actually be soothing. Or on the other hand, perhaps going to work out, lift weights, get your body moving w/ sports etc. can help you work out some of your grief and frustrations.
Every person grieves and then goes about healing in different ways. You just need to remember that you are just starting this process. Give yourself some time. You will begin to feel better gradually and as you do get out more you can either reconnect with old friends and start to make new ones.
Keep in touch and I wish you the best tonight.