Work hard and keep yourself busy
You should not become more negative after you experienced a bad breakup. You should not be a sad, depressed and pathetic person for too long as this may become a habit. You must understand that even though you lost your partner of whom you loved most, you did not lose everything.
Work hard. This is the time for you to strive harder for yourself, and achieve greater performance in your work. Work towards getting yourself a salary raise, a higher promotion, or a great offer that satisfies you.
If possible, relocate yourself to a better place. Move to another place for better job opportunities or use it as a way of staying away from your ex, and avoiding any contact. This will allow you to pay full attention for your work.
Take up more recreational activities. Go for gym sessions, cycling, walkathons and any other physical activities which will benefit you and your physical health too.
Get involved in social groups, like attending church activities, volunteering, etc. You may also practice meditations to bring about emotional, spiritual, and mental balance.
When you keep yourself busy,
You find yourself gaining greater self-confidence. Breakups make you develop low self-esteem, making you feel inferior because someone you loved the most rejects you.
You grow in maturity and become a better person. You should immerse yourself with your work and keep yourself busy with helpful activities, forcing yourself stay away from feeling depressed which may cause negative indulgence such as heavy drinking, sleeping around, or even suicide.
You do not have to worry about your future. At least after breakup, you have a stable working life or better work opportunities. You may find yourself a better future partner in the most unexpected way. Besides, through better working performance, you can prove to your ex that life without him/her still goes on.