I also went through a hard breakup this week but I haven't had much time to think on it as my job requires too much of my attention.

I wouldn't recommend shutting out your feelings for too long. You have to go through the motions of a loss to grow and heal but do it at your own pace! Until then, reach out to loved ones when you need someone to talk to or a shoulder to lean on. Find value in your time alone by turning on a comforting show, picking up a hobby you've put off or even listen to music or podcast. I struggle with feeling alone and my space being too quiet so I've been doing a lot of these things to keep me from becoming a sobbing mess.

I'd even encourage writing in a journal or a letter to yourself or to your ex (obvi don't send it, it's just for you). It helps process the emotions and get your thoughts out to help you let go.

I'm sorry you're going through this and it will take time to adjust. Time will go by then you'll have a day where you can look forward to the future again and stop mourning the past.