Never do this!
When in a spin, both feet in; i.e. hard on both clutch and brake. You want to be removing speed ASAP as you've lost control of the vehicle, but you also want to keep the engine running.
I didn't see a lot wrong, just one of those things that happens when you're pushing on, especially on that corner. Tbh if you don't spin at least once on track then you're not pushing hard enough You got very lucky though, entering grass near on sideways is the single easiest way to flip a car on trackday.