It's easy to say when someone asks you, "how you doing?" to say, "I'm 'fine', or 'OK', or 'hanging in there'". It's OK to not be OK, and it's OK to let people know you're not OK.
Know that it's OK to say that you're not OK - that means your feeling and emotions are valid, no matter what they are.
"Let the peace of Christ rule in your hearts, since as members of one body you were called to peace. And be thankful."