<human>: I dated this girl for three years and we have been through quite a bit. 
I am still bitter about the way it ended (on the first day of college) and feel bitterness for things that she has done to me.
But understandably I still feel a lot towards her and it's really beginning to wear me down.

I am wondering how I should go about breaking off contact with her as she still tries to talk to me and I'm not sure what she really wants from me.
I know that nothing good will come from continuing our relationship but I can't bring myself to ignore her texts or emails. 

Should I block her number outright? Talk to her in person? Tell her I never want to hear from her again?

Any help would be greatly appreciated.

Can you condense the text into three sentences or less?
<bot>: Broke up with ex, still have feelings for her but want to break off contact. How should I go about it?