It's truly sad that you allowed your fear of what may happen poison your moment. Or that's what it sounded like. Perhaps if you expect nothing to last you can focus on what's good right now. Or it could be that the relationship had run its course. Either way, I'm sorry you're hurt.

Never regret what you have done, only what you did not attempt. (Old saying.)

Life is too short to look back with regret, we learn from all our experiences, and our learning is the greatest treasure we have. If you have not caused irrecoverable pain with intent, then you have done nothing wrong.

All successful long term relationships rely on three things coming from both (or sometimes more) parties
Honesty, trust and the determination to make it work.
If either of you lacked any of those things in your relationship it was never going to last anyway, so just remember the pleasant moments and look on it as a learning experience you went through.

We can’t change the past anymore than we can predict the future IMO, he certainly still has feelings for you, which is why he stays in touch. I married my much younger lover, and it didn’t work on many levels. We are still friends after a period of five years of getting over the pain. Some days, when my heart aches (I still love her madly) the wish that I had never met her, or paid more attention when I first met her and she told me she hated men enters my mind. But I love her son and he loves me, since I am really the only father he really ever had. And she is responsible for my having my dog Barnie, since she adopted his mother when she was pregnant. So, all in all, the good kind of levels off the bad. And there is no way of knowing how life would have been without her in it.
So, surely you have some fond memories of your time together, don’t live in the regrets. They really serve no purpose.

You dodged a bullet on that one

I get that. I’m sorry you’re feeling regret; I’ve been right where you are. It was a relief when the relationship was over: it made me feel much lighter. I was fortunate to have no more reminders once it was over.
Focus on the future, and leave him in the rear view. As my daughter says about the past: “oh, that? It’s in the black and white; yesterday’s news!”
Big healing hug