Why did my fiancee get engaged to me just to leave me at the altar?

My wedding was about 4 days ago or rather it should of been but my fiancee never showed well shouldn't say she never showed apparently she just up and took off after all her bridesmades had left the room she was getting ready in. i honestly feel so hurt and betrayed and just honestly been feeling depressed because i love her so much and all i wanted was to spend the rest of our lives togeather but instead she betrayed me and up and left. I do not know what to do as she has been calling or coming by but when she knocks i just ignore her and when she calls i do the same she keeps saying she is sorry and was just so stressed and scared and that she rather just elope but her parents will be out like 40k =/. I just don't know what to do i mean i want her but i am now scared of her uping and leaving me when ever she gets scared now! What should i do? Advice?