How can I focus on and be motivated toward a goal or career after I failed in love or have a broken heart?

I guess this line might motivate you.

If she betrayed then

Your pain is her happiness. Be happy and let her suffer.

If she didn’t betrayed you but due to circumstances you two were separated then

Your pain is her suffering. Be happy and let her be happy.

Strange thing is love. Love is giving and not expecting anything in return.