First of all, I'm sorry for your loss. It is devastating losing a child by miscarriage. You were excited to have a child in your life now you're not. It does seem you may not be handling it well as you think you are.
You were very quick to end your relationship with her, even though you seem to care about her very much. You've shared a lot with this person, are you sure this is the best solution for you?
Sometimes, when one door closes, another one opens. So, take a minutes and actually explore your life right now. Is it possible through this tragedy, you've come to realize you'd like to have children?
Do you really want to say goodbye to her? As in never seeing her or talking to her ever again? Are you sure you don't see a future with her? You've pushed every thing aside - you are done.
Are you ready for that?