There is no useful purpose in beating yourself up. I agree with lightseeker....each time we do something and are able to look back and say "I didn't handle that well" it is an opportunity to learn and do better the next time. We're all human.
You asked "why"......and that's a much better approach than beating yourself up. If we can figure out why we do things the way we do them, we can make personal changes.
I'm sorry that things are going sideways for you right now....it happens to all of us.
gentle hugs
ke