Most Helpful Guy
Firstly, I'm sorry you're hurting and I hope for a speedy recovery.
I'd say the chances of you getting back together are slim to none. I doubt that was an answer you liked hearing, but there is a bright side if you'll hear me out. Secondly, there is no shame or harm in NOT wanting to be his friend. Do you really want to be around when he starts dating someone else? I've noticed there are three scenarios for ex's who try to remain friends. A) Fast forward a few months later and they hate each other. B) Fast forward a few months later and one of them gets their heart broken all over again when the other starts dating someone new, or C) Fast forward a few months and they are good friends. Sadly, I have noticed A and B are the two most common outcomes. If you decide to stay this guy's friend, then I sincerely hope you remain good friends. However, it might be worth considering just being friendly acquaintances. You can be polite. You can be civil. You can be friendly. In fact you should be all those things. However, if your heart can't handle being his friend, there's no shame in that. You don't even have to make a formal announcement (thus keeping things open if, at some time in the future, you think you could really be a friend to him). Just limit your contact.
The good news is that in limiting your contact, you are speeding up the healing process. I've noticed prolonged contact tends to prolong the recovery. By speeding up the healing process, you won't be tying your feelings into someone who doesn't seem to care for you the way you care for him. You are 18, and have most of your life ahead of you, my dear. In speeding up the healing process, you'll be ready to bat those eyelashes at the next Sir Awesome who comes your way, instead of not noticing him because you're too into someone who isn't into you. You seemed to have wooed this guy you broke up with, so why not get out there as quick as you can and do it to someone who'll be right for you? I wish you all the best and you take care now.