Ruby, you do indeed now have to think of yourself and put yourself first. However, if he gets in touch and you're feeling strong, and curious, why not give it a go? I don't mean leap into a relationship, if invited, I mean meet as people who once knew each other.
Have a coffee or a meal.
I'm on very good terms with a few men I knew well long ago. I occasionally get together with one or other and mull over old times, have a laugh. They are my friends now, the fires have cooled to embers. There's a lot of shared history.
Then of course there's the one who still pops up on FB or emails me out of the blue.Clearly has NO IDEA that although I no longer fear seeing him I'd certainly never want to. He probably doesn't understand why I got away or what was wrong with the relationship. His recollections must be so different from mine, I couldn't, wouldn't, even try to explain.
Anyway I hope your son goes off to university ready to tackle this new stage of his life. All the best!