Question

تو که اینقدر بی رحم و کینه ای نبودی!در انتخابم خیلی اشتباه کردم....

Answer 1

You were not cruel / stonyhearted / unmerciful and revengful this much. (I think) I have made a big mistake in my selection / choice about you.

Answer 2

You have not been so merciless and unforgiving. I've made a very bad choice.

Answer 3

But you were not so ruthless and rancorous/spiteful. I made a great mistakes in my pick/selection.