"Closure" isn't going to make you feel better.
Getting dumped sucks. And we're conditioned through religion (or a rudimentary understanding of physics) that everything happens for a reason. Our self-importance and a terrifying dread that existence may be a terrible coincidence, followed by a random ALF GIF, sandwiched between a series of totally unrelated events make us look for meaning in everything that happens.
You lie to yourself and say that you want to know "why" so you can either "be better" or avoid a similar situation going forward. In fact, you may even demand your newly-minted ex tell you why you're breaking up because you deserve closure.
"Closure" isn't going to make you feel better. "Closure" isn't going to either return your appetite or throttle it, depending on how you grieve. "Closure" isn't going to make you learn to trust any more. Your ex doesn't owe you "closure" — because it doesn't exist.
Typically, when I hear a person say they want closure, what they're really looking for is for the ex to prostrate himself (or herself...) in some way that makes it clear that it's unequivocally "not you, it's me." In most cases, the breakup is inevitable as it's ultra-rare that a relationship can work for one person if it's not working for the other.
However, in our minds, we're the hero of the story and want to make it very clear who the villain is, especially to the villain. This inner narrative, in a number of ways, keeps us sane.
Does hearing "We're not at the same place in our lives" mend your heart? Does a blubbery lamentation that "I'm no longer attracted to you" make you want to make positive changes? Does the dagger named "I fell in love with someone else, I didn't mean to, I'm so sorry" inspire you in some kind of magical way?
I'm not interested in absolving anyone of their sins. I'm also not interested in the inquisition of the person who was brave enough to end a non-functioning relationship. Sure, ghosting is an affront to God and all the angels, but I prefer it to a long conversation of what I could have done to be a more perfect partner for the lady I'll never see naked again.
And that is the real crux of closure. Until either time or a distraction fill your mind; no 12,000 word essay on "why you're better off without me, my queen" is going to put your mind at ease.
There's a good chance even if you're a truly strong and woke individual, you will never erase the special place and "what if" you have in your heart for you ex. It sucks, but it's one of the beautiful parts of being mortals with imperfect memory.
Your best bet is severing contact and hoping you'll both be (and meet) the right person at the right time and place.
Maybe I'm being too hard on closure by denying its existence. Noted biological anthropologist Helen Fisher recommends "just make one up" when it comes to backdating the reason for a breakup. Dr. Fisher's "love is an inside job" game is strong, as she often credits positive allusions as a key building block to successful relationships.
Either way, until we invent the device from Eternal Sunshine Of The Spotless Mind, we're stuck with our exes stinking up our brains no matter how many times we force them to sing us to sleep with "Sorry Ms, Jackson."