Actually, I would argue that Shawn's dad doesn't really cope with his son's condition at all. In fact, he does just about everything he can to avoid having to cope with it. Instead of devising a coping mechanism to deal with the consequences of Shawn's serious disability he simply ups sticks and leaves his family, no longer able to handle having a disabled son.

Though Shawn's dad is undoubtedly selfish in leaving his family, he's been driven to take this action by a deep-seated frustration at not being able to communicate with his son. Shawn's cerebral palsy means that his dad cannot enjoy the kind of father/son relationship that he so desperately craves. One can understand, therefore, why he's so incredibly frustrated and unable to cope.

Once separated from his family, Shawn's dad finds it a little easier to handle things, but only just. He's able to let off some steam by writing a poem detailing the stresses and strains of living with a disabled child. The poem is so successful that it wins Shawn's dad a Pulitzer Prize. Inevitably, this makes him something of a celebrity, and he revels in all the attention. Strictly speaking, though, this is not quite coping as Shawn's dad still doesn't live with his son.