I think you are very stong, you are aware what your needs are and able to set boundaries (like not answering his emails). That's not easy to do at all after such a long time.
I understand that you'd like to have some answers on what was the reason this ended up the way it did, and you might get some answers, but I think it does not necessarily mean that you "did something wrong". Sure, it's helpful to understand the pattern if there is one, but sometimes connections just naturally fall apart and go in different directions. But the pain is still there, I understand.