Most Helpful Girl
First and foremost - time. The more time passes, the less shitty you'll feel.
The question is rather, how to make enough time pass without succumbing to depression and becoming bitter, or worse, losing hope and wanting to harm yourself.
There is no one-solution-fits-all answer, obviously. But judging from my personal experience (and I've been there) and from what I've observed in my friends, as well as what common sense tells me, there are certain things that will definitely help and makes things easier (or less hard, at least).
1. Do not isolate yourself. Feeling like shit understandably makes us want to crawl under a blanket and stay there for a long time. And that's totally fine and legitimate in the immediate aftermath, for a while. But it's essential to get up again and go out and meet people. Stay social.
2. Talk to people that you trust about your situation. They will give you all sorts of different inputs, and that's good. Hearing different perspectives will help you see things differently, especially when coming from people you care about. This will most likely also make you see the positive apsects.
3. Distract yourself. Keep yourself busy. Focus on things that are important to you, especially things that you might have neglected because of her.
4. Change stuff. Whatever it is. Your hair, your beard, your furniture. Anything. It can be small things. get rid of old stuff that you don't use or need anymore. This helps you move on.
5. Break off all contact, including deleting her from all social media. Looking her up on social media will just make things harder and take longer. Do not talk to her. It will only do you more harm.
6. Stop talking about it. I know this is a contradiction to #2, but what I mean is to eventually stop talking about it when you've said it all and everyone's told you what they had to say about it. At some point it's very important for you to stop actively discussing this topic.
7. Focus on your anger instead of your sadness. It's natural to initially be sad and wanting her back, but eventually you'll realize that you can be glad you got rid of her. She cheated on you. She hurt you. You should be angry at her. Be angry.
8. Last but not least, think about new girls. You don't have to rush this, but it's good to at least think about meeting someone new. Because to ultimately answer your question: to get through the pain, you need to stop looking back and start looking forward.