Perhaps you had doubts about the relationship as well? Make sure he also knows you just want to be single for a little while because the relationship stuff was a little too much.
Particularly that second one but before I open up about that I want you to get one thing through your head.
So you pull the trigger.
Before you send something you may regret, think through it a couple times, and check in with yourself to confirm you are in the right mindset.
That will change his tune fast.
This can include things like giving yourself a bubble bath, buying yourself flowers or treating yourself to a nice night on the town.
This is especially true for the person who was left.