When you are a writer can you get in legal trouble for telling events that happened in your life?

Basically, I am writing a story/book/whatever and want to share events that happened in my life. However, specifically, the story would concern an ex. A spiteful ex. And while its comedically funny, she had her funny bone surgically removed and stuck up her ***. So, my question is this. While her name will be changed and the scenario somewhat changed, I dont want legal retaliation for the aforementioned stick (or bone) in the ***. What are the limits for things like this?