When does no contact get easier?

It’s been a week. I was doing super well yesterday, I thought to myself “maybe I will move on from this fully in a few weeks.. wow”. However, today, all the feelings came back, hitting my like a truck. The thought that he’d never come back, that maybe I should try one last time and break NC etc . On top of that, I didn’t eat all day because I just can’t and breathing is so difficult, almost like someone has their foot on my chest.