Don't quit your job. Quitting will give you more free time on your hands, and that's not what you need right now. You have weekends as your trial to see how mentally screwed up you will be if you quit your job.
When working try to focus on your work, think of it as your responsibility. Humans generally take their responsibilities very seriously, so for a few hours every day, those thoughts of ex should keep at bay.
Don't ever bottle up your feelings and emotions. It's okay if you don't want to be vulnerable in front of someone else, but be vulnerable when alone. Let those tears out, scream if you need to. Don't ever suppress these emotions, they rot you from inside.
Go to gym, for a walk, talk to family and friends. This helps in speeding up the healing process as your mind and body find have resources to release the emotional buildup in a healthy way.
Don't take any impulsive decisions, don't go back to someone who left you behind. Don't go in another relationship when you are already suffering, rebounds are not worth it. And don't do shitty things like substance abuse or harming yourself.
In a few months all the pain will dull down and there won't be tears. Live your life buddy. Life has so much more to offer to you.