This is depression. Cannot stress enough that you need to push yourself to keep living as you normally do. When I went thru my first serious breakup I self-isolated so bad, lost some friends, and failed all my classes that semester. That was the hardest thing to recover from. Trust that the apathy WILL go away eventually and you will go back to normal, don't make your future self's life harder.
Sounds alot like my first breakup. I was depressed like this for months, maybe even a year. Cried every day. Still had to get up and get shit done, but I didn’t enjoy it. I didn’t want to take care of myself, but I still had to do it. I just dwelled in my thoughts and let that jerk steal my joy. It’s okay to feel sad. It’s grief. And grief comes and goes. Take the time you need to feel what you need to feel, but don’t let it cost you your health and well being.
Five days is still pretty raw, but that moment’s come and it’s gone. Take the weekend to ride it out, and then try to start fresh Monday. Doesn’t have to be anything big. Start small. Make your bed in the morning. Take a shower, make a nice breakfast or cup of coffee. Start taking care of yourself because you deserve to be taken care of and shown love.