Your experience is extremely similar to mine.
Very, very similar.
My recommendation is quite the opposite. I called the shot after 8 years (and after getting engaged), and with hindsight it was possibly the worst thing I have ever done in my entire life. Never recovered.
Councilling. Open up your thoughts with her, directly. I mean, say "I'm thinking about it" to her. Explain the reasons why. Debate could have saved my life, I've been miserable for a long time since.