Ex slid into my DMs and is giving mixed signals

Long story short, I dated this guy two years ago for about six months. It ended because he’d just gotten divorced and wasn’t ready to be serious. He ended up ghosting me. Fast forward two years later, he reached out on Instagram checking in and we DMed back and forth catching up, talking until like 1 in the morning. He apologized for how we ended things, and he was being very flirty in the messages. He also told me that he’s seen me quite a few times over the last few months (we live in different counties but apparently he’s working somewhere like half a mile away from where I live).

We chatted briefly the next day, and then nothing for a few days. Sent him a message over the weekend, he responded and we had a brief conversation. I asked him if he’d like to get coffee sometime and catch up in person. It’s now Wednesday and he still hasn’t opened the message, but he’s been active sporadically and watched through my insta stories today. It’s also worth noting that he unfollowed me on Instagram at some point in the last year, and then re-followed me after I responded to his initial message.

I’ve always considered this guy as a sort of “the one that got away”. But now I am very confused. Is he interested? Is he not? Is he blowing me off? Did he learn nothing from the situation two years ago? Do I say screw it and move on, or do I follow up?