Focusing on applications during a hard breakup

My relationship just ended after 3 years together. She was great but long story short she lost interest in me and got progressively colder to me until completely ignoring me, it was hurting me too much so I decided to close things off.

After all this time I am obviously emotionally destroyed and I really have no mental energy to focus on something else. Sadly, this happened in the worst possible moment, as I am now starting to seriously apply for jobs and I really can't do it right now.

What is your advice? How do you focus on work when you are going through a very hard time personally?