How does karma work?

How does karma work? Does it play on the bad you did only, or does it accept your attempt to fix it?

Recently, I inadvertently hurt someone. I attempted to fix it, was honest and straight forward, and remorseful....and seemed to only make it worse. While trying to fix the problem, I succeeded in only making myself feel the burden released, but making that person feel worse. That was never my intentions and I feel horrible for it. At this point, I'm unsure I can right the wrongs.

However, I did try. I attempted to make ammends for my indiscretions, with the best of intentions in mind. The offended reacted as I hoped they wouldn't...and in the end, only managed to hurt me more than I hurt them. They have made no attempt to fix it....nor is it likely they will.

So, how does karma work? Am I faulted on the initial errors, and my attempt to fix it is ignored? Is my error forgiven because of my attempt to right a wrong? Do they cancel eachother out? Or are both weighed and balanced, and the appropriate course is taken? Does the person I hurt, who hurt me back, face karma as well? And if I do suffer from my errors, how do I fix them when my attempt to right the wrong I did was only made worse?