@Confusedcutie3,
Well, we can't necessarily promise wise advice. We'll try.
Clearly something is still irking him about all of this. It might be a lack of closure but the truth is, closure is pretty damned overrated. We often don't get it in life.
He's still got to move on.
I like communication. So, talk! Both of you, together, to each other.
Non-accusatory.
This is to just have a discussion about this. Not to talk about it hurting anyone, just to think about why he's still on about it a year and a half later. And tell him - you need to think about other things and talk about other things. Figure out when you're starting, and stop it in its tracks.
Not an ultimatum; this is more to make it clear that it's been a while and he needs to check himself.
If it continues, there's always counseling - he may need to find out why he's still obsessed.