Most Helpful Guy
It's nearly impossible to remain friends with someone you still have feelings for, or who still has feelings for you. One person will always want "more", and are effectively torturing themselves by being around the person they have such strong feelings for. That will make things awkward and uncomfortable, and it will either push the less-interested person away or lead to a big fight/confrontation/breakdown.
When you break up with someone, the smart, and often ONLY workable plan is to make a clean, complete break from them so you can emotionally heal. You can be civil to them if you run into them, but you don't try to be "friends."1