Based on your 'slap in the face' quote it seems you feel you were owed the starting job this year...
I hope you learn that you aren't owed anything in life.
'Playing time' is earned in football and in life.
Trevor Lawrence earned this start with his performance in practice and in last Saturdays game. A game is which the offense seemed hapless under your command.
Had you stuck it out and continued to compete, there's the chance that you could've earned the job back. However, you've decided to run from that competition and quit on your teammates and yourself.
Best of luck and hope you learn and grow from this situation. Looking back it's very possible you'll end up wishing you'd done it differently.