Most Helpful Guy
Things may have ended badly, but that doesn't mean they have to stay bad. Maybe some things were just said out of anger. Just because you two broke up doesn't mean she doesn't still care about you as a friend, even if she hasn't contacted you (she may have been giving you space since you also weren't contacting her).
Point is, exes can be friends, sometimes even best friends. After all, you've likely already shared more of yourselves with one another than regular friends do, so you had a stronger bond. I know the break up between me and my girlfriend didn't stop us from being each others' best friend. We still talk to each other about everything. The only difference really is that there's nothing romantic between us anymore. No harm in trying to restrengthen your friendship. The way I usually see it is that it's better to have someone you really love(d) in your life, even if it's not quite in the way you had imagined, than not have them in it at all.