I can only speak of my experience with divorce. My initial reaction wasn't joy. It feels like a personal failure, and it's a huge change in your personal life, and it up ends things that seemed like long term plans. Once I made the adjustment to the new normal, I think I was a happier person. While there was a time in that relationship where we were both happy, there came a time when neither of us were. It wasn't a bad divorce. We agreed on how to split everything up without involving lawyers. We always treated each other with respect, and neither harbors any ill will toward the other. I'm more than content with my life since the split. I think she'd say the same.
Good for you Mule. As another poster mentioned, it's not good to stay in an unhappy Marriage. My point was to say no one is ever "happy" over the prospect of Divorce. But as you said, in time you can learn to heal from it.