Break-ups are rough at the best of times, but I feel like the ones during the pandemic have been extra tough and I'm sorry you're in the midst of one. You did do the right thing by talking with him rather than having sex with someone else behind his back. Unfortunately, life is full of times when doing the right thing doesn't lead to us getting what we hoped for.
While plenty of people remain friends after breaking up, that often tends to go best when it doesn't happen right after the break up does and one of the people involved isn't still harboring romantic feelings for the other person. So, the kindest thing you might be able to do for yourself right now is take some space from any kind of relationship with him. Since you two are long distance, that would mean things like not contacting him for awhile or unfollowing him on social media so you're not being constantly reminded of him. Do those feel like steps you can take?
In terms of more general advice, if you haven't already seen this piece, it has a lot of things you can do to get through a break-up: Getting Through a Breakup Without Actually Breaking