How about you tell him
彼に行ったらどうだい - Weblio Email例文集
A child does not know how deeply concerned his parents are about him.
親の心子知らず. - 研究社 新和英中辞典
Hate is too mild a word for how I feel about him.
憎んでもなお余りあるやつだ
http://ejje.weblio.jp/sentence/content/how+about+him