Let me see if I get this right:-
You said you wanted to finish everything...I assume the relationship.
You then changed you mind..I assume again the relationship
If I am right she might be angry or hurt and wants to think. If you wanted to end the relationship she might be wondering why. She wants to come to terms with that even though you changed your mind. Changing your mind does not change the fact that you were finishing it.
SMS her to tell her how you feel.......that is you are very sorry and you made a mistake, you were under stress and not thinking clearly.
Don't actually call her yet, wait a few days after sending her the message. she may get back to you. Send her some flowers or chocolate, or something meaningful.