Dear Richard,
You have taken a wise decision by ending relationship with her. As you mentioned your girl was not worthy of your love and trust.
She has broken your trust as she isn't reveals her abusive relationship with someone else with you. Trust is the foundation of a perfect relationship. When both of you trust each other completely and understand each other, it prevents insecurities and frustrations from ever cropping up. But she has no values for your trust.
I understand that you love her without any self benefit, but in reality she haven't any such feelings for you.
She was only trying to make use of you throughout your friendship
Be strong, forget and discard such kind of people in your life.