In a 9x13 baking dish, mix together the graham cracker crumbs, sugar, and melted butter, until well combined.
Press graham cracker crust mixture firmly into bottom of 9x13 pan with the bottom of a measuring cup, or something hard and flat. Let crust chill in the refrigerator while you make the filling.
Filling
In a large bowl, use an electric mixer to beat the softened cream cheese until smooth. Then mix in the sweetened condensed milk and lemon juice.
Fold the whipped topping into the cream cheese mixture, until incorporated.
Pour mixture onto the prepared crust and spread until mostly even. Let set in the refrigerator for an hour or two.
Topping
Layer sliced strawberries over top of the cheesecake.
In a saucepan, mix together the sugar and cornstarch. Stir in boiling water and cook over medium heat until mixture just begins to thicken, only a few minutes. Remove from heat.
Stir in the gelatin powder, until smooth. Let cool to room temperature.
Pour gelatin mixture over the strawberries and cheesecake, until strawberries are evenly covered. Refrigerate for about 2 hours, until topping is set.