My indoor only cat went missing three weeks ago. I am distressed, devastated and do not know how to cope with?

He is 5 years old neutered and skittish. He probably started chasing a mouse and went into a construction zone, got scared by the cars and noises and ran away somewhere. I have been sick worrying about him..of what he eats, what he drinks and where he sleeps... Would he be confused? Do cats have emotions that they cry for long periods? Would he be confused looking for home? Do they miss home? For how long? It has been three weeks and I am not sure if he will ever come back. They say that homing instincts do not work if the cat was an indoor cat displaced in fear or accidents. We searched everywhere, humane society, flyers, ads, door to door, within a 7 kms radius, but I am not able to locate him. I find it hard to cope up with this unknown....uncertainity. Every second I am thinking of where he is and if he is thinking of us.... Can anybody tell if he is roaming around thinking of home? I am dying inside and am losing hope. I know we cannot read a cat's mind, but I am sick worrying about what he is thinking, what he is eating. Food was served to him before, and now the past three weeks, he must be scavenging for food..and he never even hurt an ant. I will be a little okay if I know that cats do not grieve and cry all night looking for the owners... I am so heart broken and it is increasing day by day...I am still frantically searching for him, but just dont know where to look anymore because I am getting false leads from many places. Your thoughts will be appreciated... P