How can I phrase why I was let go from a job?

I had this job that one day my boss decided she just didn't like me anymore. A few weeks earlier she had written a glowing description of me in the newsletter, and then suddenly she hated me and decided to make my life hell. (I am not the first person there she's turned on). I was subjected to humiliation among other things, and pretty much set up to fail. I tried to just tough it out because she was retiring soon. A month before she was to retire, she decided to let me go. It was like her final power trip. I don't want to sound snarky or bitter when describing this, but I also don't want to sound like it was all my fault. Anyone have any ideas of what I can say?