Breakups suck. There is no other way to say it. But... the good thing about breakups is that they can be seen as a good thing rather than a bad thing. I think the first step to getting over a breakup is to take time to grieve. Your life is going to be different. A whole person is removed from your life. Removed from your routine.
It's OK to take a day to be sad.
I usually take one to two days to be sad and eat a lot of food. You can't just skip over the loss and think that you will recover. You can't do that. Take your two or so days to be sad. No longer than a week. Don't wallow in your dirty, crumb covered sheets.
Once you have taken your grieving time, get your butt up.
Take a shower and leave your house. Put on your favorite outfit and do whatever you need to to make yourself feel better. Go do something. It can be something as small as getting a coffee or walking with friends. Do something with people. Don't become a recluse and isolate yourself.
Do not post on social media.
It is SO tempting to tweet about how sad you are or post a sad snap but don't. Don't let your ex have that much power over you. Don't give them the satisfaction of how sad you are without them. They are going to move on, so you should too. You should also mute them or unfollow your ex. There is no reason to get upset every time you open your phone and see their face. It's not "childish" or "petty" it's smart.
You have to put yourself first and be selfish at this time.
Once you allow yourself to climb out of your dark hole of pity, jump back into life. Keep your chin up and keep going. The best way to "win" in the breakup is to be happy and move on without them. You may fall, you will get random slip-ups of sadness, but you will be OK. Take what you have learned in the relationship and remember that part. Notice what worked and what didn't.
You are fine, it's just a breakup not the end of the world. You got this.