At some point in your life, you've gone through a break-up in one form or another. Usually, you want closure. You assume that the best way to get closure is by talking to the other person. You want to know why he didn't think you were worth it, whether he actually had feelings or was just using you to pass the time. You want to know if there's any way that it can still work out.. if maybe time will bring the two of you back together.
Asking those questions will not give you peace of mind. When you do ask those questions there's a few things that could happen: you learn the truth and realize there's nothing more you can do, you find out something that you really didn't want to know and end up more hurt than before, you end up being told lies that he thinks will give you comfort, or you realize you were looking for deep answers when all his thoughts on the situation were pretty shallow.
At this point, nothing he tells you will give you peace of mind, and nothing that you say will change his mind.
Most importantly, when you have all those questions you want to ask him for closure, you're giving him power over you-- again. Not only did he have the power to hurt you, but if you ask those questions then he also has the power to give peace to your mind. He doesn't deserve that power, you deserve that power.
What's really hurting you is the fact that it ended. Yes, not knowing exactly what his reasons were or not knowing if he's telling the truth about why he ended things sucks, but it doesn't hurt.
The fact that it ended is something that you need to heal from, and you won't heal by seeking closure. By seeking closure you're giving him more pieces of you than you already have, and you're better of keeping whatever's left of you intact.
It's easier to heal your heart by saying, "That sucked, I deserve better," than to spend time asking questions that won't change anything and won't make you feel better.
Most of the time when someone leaves, you blame yourself. You think you're not attractive enough, not skinny enough, not smart enough, just generally not enough. This mindset is easy to fall into and honestly, there's no way to not think it. What you can work on, is thinking that way for less time. Let the thought come, and let it go. Remember you are good enough and if someone doesn't see that then that's on him, not you.
It sucks knowing that you can't change anything.
It sucks that you allowed someone into the deeper parts of your life and now you're left wondering why he acted as if he cared so much when he just ended up leaving. It sucks that you weren't what he wanted. It sucks walking around with all of these little pieces of other people that are just heavyweight that you can't seem to get rid of.
Stop trying to hold on to what could've been. Stop seeking out closure from whoever hurt you. Figure out a way to find peace of mind in yourself, because no one else deserves that power.