Chris says that her has been "a good son too long,a good sucker". what does he mean

That "her" has been a good son? I'm not sure to who or what you are referring.

Really he means that loyalty to his family is destroying his own sense of well being. Chris is tired of pretending the lies his family lives by and shoves under the rug are true, he is tired of pretending that everything is all right.

Chris believes that he has always been a loyal son to his father, that he has put aside his own desires to please his family and prove his loyalty. The fact that he is maturing has led him to a place where he is ready to break away, get married, and even raise a family of his own. Larry's disappearance (death) left Chris unaable to separate his own identity because he felt responsible and didn't want to disappoint his parents. He stayed by them because he loved, respected, and wanted to fill an impossible void. After hearing about his father's part in the "parts" scam, his feelings change, and he is ready to live for himself.