Aw
I think she was just a girl you really, really loved. Don't feel bad about trying to mend it and being clingy.
I do this behavior too. It's an honest reaction to your emotions. You're still in a cloud of hurt and you want to fix it so you become desperate. Then you heal a little and begin to think with your brain and you're like "why did I do that?"
I think you've never done it before because you've never felt enough pain from a loss. The only thing you can try and do is wait it out at least a week after a breakup before contact to let the smoke clear a little. I need to work on this too.