I do have concern for the woman's safety should she attempt to return to a man who says he feels rage.
Give me a break ehBeth!
People (even men) get angry. This is a part of being human. When you are angry the healthy thing to do is express it. That is all he did in this post. He said "I am very angry".
What did he say that would give you any reason to have concern. He said "I am very angry", and he said "I don't want her to come back". Not only didn't he say anything that would raise any cause for concern, he didn't even say anything bad against her. He didn't even call her any names.
How much more of a healthy can you possibly imagine? He is doing what anyone would tell you to do. When you are angry you express your emotion in a healthy, non-threatening way. He is even owning up to his anger. I don't even see him blaming this woman for what he is feeling.
I think you are being absolutely ridiculous ehBeth. Maybe your reaction says more about your issues than about his.