After a sudden break up of a serious relationship can lingering feeling cause doubt & change of heart/mind?

My ex girlfriend & I had a falling out 3 weeks ago. We are in our 30's & were together 4 months(seemed a natural fit, spent a lot of time together, were happy, planning to live together, she was asking about kids for future). i made a mistake (not cheating, used poor judgment) & upset her to the point it brought up a bad past memory. i felt horrible as i never wanted to upset her. she decided to break off relationship. i felt guilty, shocked & sad. Eventually most of my feeling turned to anger because she didn't talk to me & handled situation poorly. (we still haven't talked, i sent a few messages & texts-at first responded w/ anger from her & last couple no response) I still miss her as i thought she could have been the one. We were well on our way toward love. So w/ recent past feelings so strong can that cause doubt on a breakup mainly caused from a single issue(we had issues w/ communication, moving away & children but talked them out). I feel she over reacted & made a mistake w/ handling of situation. In time, is a change of mind/heart by her realistic?