You need to find out about WHY your ex is behaving as such that she doesn't care about how you feel. But if you want to spare yourself from further hurt and confusion, you had better 'man-up' and be stronger to preserve yourself and be away with her (good riddance, ditch). There are better, maturer, and probably kind and worth befriending.
But if, she genuinely cares for you and loves you and you feel the same way, try to talk and work it out.