A relationship break up is something no one ever wants to have to deal with. It's painful and if you were blindsided you feel like you have been kicked in the teeth. Even if you knew it was coming you still need time to learn to deal. Learning to be without that one person who has been around for so long takes time.
There are steps you can take to make yourself feel better. Right off the bat you might feel like you just want to be alone. Go ahead. Tell all your family and friends you are going to take a couple of days just to cry it out and think things over and make a plan. This step is crucial and can be good for you as long as it is only for a couple of days. Make a plan to have one of your friends call you or stop by after a couple of days to make sure everything is alright.
During your alone time, make a plan for your immediate future. A relationship break up is not the end of the world and you are going to need a plan. You know the two of you had not been getting along recently and now you wonder if there was something you could have done differently to keep the two of you together. This is normal. Try not to spend too much time on this though because the important thing now is learning to get on with your life.
During your couple of days of being alone there are some healthy things you can do to start making a new life for yourself. One of them is boxing up all of the things that remind you of your ex and putting them away in storage. All those things you accumulated together need to be gone. Give them all to him if you feel like it. If you can't bear to part with them because they are a part of your life then at least get them out of sight for right now.
Another healthy way to handle things is to write down how you feel about the whole thing. Buy yourself a journal or even just a notebook will do. Doing this will help put things into perspective and help you keep your feelings in order. This is very healing and you can refer back to it whenever you need to.
When your couple of days of solitude are over, call your best girlfriend and get out of the house for awhile. Go to lunch, or go shopping, or go to the park and just talk. The fresh air will do you good and so will making contact with your friend. She will have worried about you and having contact will put her mind at ease also.
After a relationship break up you will feel as though you are undesirable. Getting in touch with your friends after a couple of days will show you that they still love you and are there to support you when going through this terrible time in your life.