Why was this lady so harsh in ending our relationship?

There had to some reason, good or not so good, that she ended things so horribly mean. You could have done something or said something hurtful to her or she could just have felt bad about seeing someone else and it was easier for her to split up with her acting angry rather than doing it respectably. If she knew she did not deserve respect over how she had been doing you wrong, cheating or whatever, it would be easier for her to act mad at you so she could actually pull off leaving. Chicken **it! That's what she sounds like.