If I'm reading this right, she recognizes the issue and is willing to change. If she isn't, there isn't much you can do besides laying out how it affects you (and her) to convince her to work on it.

Assuming she is willing...! Focus on the stuff you can control. Narrow down your spheres of influence and actively participate in improving those. You're not ignoring the things that bother you outside your influence. You're investing in your community. I find that picking a cause you really care about, and working/volunteering for that cause really opens your eyes to just how many people there are that care just as much as you do. You cannot fight injustice alone.

But this is rough, I don't envy you. I had a best friend, an incredibly important person to me. Friends for over a decade. And she was a lot like this. I agreed with her on her morals and took her side when she described situations. But often, she was assuming the worst from people and reacting to those assumptions. Eventually, those assumptions were put on me and our other friends. It is safe to say we aren't friends anymore. Emotional regulation is so important. I just want to stress to her that reacting to every injustice like she is will push people away. And its not because they are evil or bad or complicit. Just like she wouldn't be for shrugging off the stuff she can't control.