Well, he broke up with you. Him having baggage or not being ready, that's all excuses if you ask me.

Maybe he has doubts now. Maybe he thought he could get someone else, 'better' in his eyes, but it didn't work out. Maybe he is using you as he transitions into a relationship he does care about. Maybe he just wanted to know you were doing ok so he doesn't feel bad about in what state he left you.

So he did message you. Did he tell you if he changed his mind? Did you tell him you aren't comfortable with him contacting you as long as he hasn't changed his mind?

You both seem way too old to beat around the bush with text messages.
And if you really want to give him a monologue he cannot interrupt, you can email him. Handwritten letters is a bit too old-fashioned. If you want to talk to him, call him to meet to talk.
Texting 'saying hi', that all seems pointless.

Maybe my post is a bit strange, but I just don't understand the 'It wasn't a talk about getting back together, but it was clear that we both aren't ready to let go'. What does that mean? You both prefer to be in limbo, not knowing where this is going?

Anyway, in the next sentence you say he wants to meet, but apparently you didn't make concrete plans? Why? I mean, he brought it up. So you said neither yes or no, and he dropped the subject? I mean, I doubt he brought it up, you said 'yes', then he said neither 'yes' or 'no', and you both moved on to some other subject, leaving it unresolved?