It’s not clear what you mean by “got destroyed”. Your opponent ran 4 racks on you? You missed 3 hangars?
Was every shot a good process, or were you distracted by outcome thinking? In my experience the more you think about winning and losing, the less you focus and the worse you do.
Yep. Just play in the moment. Don't beat yourself up for that last mistake -- it's in the past. And don't think about winning or losing -- it's in the future. As the saying goes..... If you stand with one foot in the past and one foot in the future, you piss all over the present.