Why can’t I let go of her

Ok guys I need help in getting over my ex, I loved her beyond words and would have done anything for her , however though she could be loving at times she was very harsh and hurtful with her words as well as abusive both physically, emotionally and Verbally. On her worst days she made me feel like I was the worst person in the world and on her best days I was an angel. I decided to leave her even though she cried and begged but I still regret leaving her and would take her back in a heart beat.

please what’s wrong with me and how can I get over this feeling?