My friend has a problem with forgiveness/ why is our friendship unhealthy?

In gerenal we get along really well and have a ton of thing in common and have a similar disposition. Three years ago we were really close and talked every day for hours. We had a huge argument back in March and still doesn't wanna talk or hang out with me, don't really wanna get into details but she was even still holding onto a grudge from some very few small things I did wrong… A year ago. A few days after the argument we talked for a while and things were oksish. I wanted to hang out at her house but she probably thought I'd bring up the subject about what led us to our argument. She said I made her hate herself and didnt wanna see me again. Its to the point where she switches quickly and is almost like two different people, its exhausting for me since I carry around alot of emotions. I kinda feel bad for her cause she's also has alot of trust issues with people, since she's been used and treated badly alot and doesn't seem to trust me that well and just misunderstands me. In reality, I'm a very trustworthy loyal person that will do anything for my friends. I seriously don't have this problem with the rest of my friends. Why is she like this? It doesn’t seem normal or healthy for her to be angry at me for this long; its been 6 months