Stir lemon gelatin and boiling water in a bowl until gelatin has dissolved; set aside to cool.

Stir crushed pineapple with juice and sugar together in a small saucepan over medium heat until sugar has dissolved and mixture comes to a simmer. Set pineapple mixture aside to cool.

Transfer cooled gelatin and pineapple mixture to a serving dish or mold; stir pimento cheese into mix until completely combined. Gently fold whipped topping into gelatin mixture. Refrigerate overnight.