After being with someone for so long, acting as though they were your other half, it's hard to be alone and "find yourself" after the breakup. Now everyone is different, every relationship is different. While my relationship was very intimate and dependent, others could be more so just a friendly relationship.
When you first breakup it hits you like a thousand bricks. It's hard to realize what your life is going to look like post-relationship, especially if you saw yourself with the person forever. As someone who is finally getting over this first stage of the breakup, I can say that it's a long and rough route, but the pain does eventually go away.
You'll want to be alone for a long time. Away from family, friends, your job, etc. Everyone will start to wonder why you are distancing yourself and make excuses for you to come out and have fun. You don't have to listen to them. If you need time alone, take that time alone - but also know that your true friends will not quit asking you how you are doing because they care. While it might seem annoying, just know they are coming from a good place.
When you are finally ready to go out in public again - when most of the tears have been shed and your heart is starting to feel whole again, just remember to be you. It's okay to be sad still, because nobody is expecting you to be any different, but try and do some things you enjoy and not worry so much about your ex. Go out with your friends, hang out with family, and do things on your own.
Learning to be single again can be difficult, but becoming friends with yourself and learning to enjoy being alone with help it all go more smoothly. Having a partner is great, but you also don’t have to be with someone. It’s a hard reality for some people to understand (and I realize that some people do just need a partner to be happy and that’s okay) but being alone is okay...sometimes it’s even better than dating.