Input please!

So I ended things with my fwb. It sucked cuz we were basically in a relationship just no title. From the beginning we always said when we decided to end things it would suck cuz we would both miss the friendship. Well we planned to go to lunch this week to try and get back to the friendship. Don’t get me wrong I know it’s probably impossible to getting back to being friends but I wanna try. Well I’m not gonna lie this is a lot harder for me than I thought. Well now I’m doubting lunch cuz idk how to be around him now that I can’t be who I used to be. Honestly I feel like this is so easy for him. So my question is should we have lunch during the week and take the chance of going back to work upset. Or having lunch on the weekend or seeing each other out side of work in case it gets more intense than I planned?