Yeah, I noticed on Reddit that divorce is the most typical reason why men start to improve. For some reason, men in long-term relationships kinda forget to do many cool things for themselves. And when the relationship ends, they start doing all these things and become much more interesting. Looks like it worked for you too! Congratulations on the social exercises, sports and studying, and please don't stop :-)
Reading the first part of your story was really depressing though. Why did you endure so much, why didn't you just dump her immediately? Did someone advise you to be "understanding" in that kind of situation? If so, that person probably shouldn't be giving advice.
This is the second post about Dealing with a Major Personal Crisis. The recount of the crisis is complete now. Please continue reading there but comment here.
The reasons for posting it this way are explained at the end of the link. I hope this approach does what I want it to.