The short answer is that its tough.
You may have ( probably have ) formed strong bonds with some of the folks that were let go. Consider how much time you spend with your co-workders -- in some cases its more than the folks in your personal life.
To answer youyour question, the easiest way I have gotten through youra similar situation in the past is to dive deep into my work and to focus on your remaining relationships with the people still with the company and look to forge new ones. Most of the remaining employees probably feel very similiar to how you feel.