In 5 separate containers (each able to hold more than 1 cup) add 1 cup of boiling water to each packet of jello powder. Stir them constantly for about 2 minutes or until all jello powder is dissolved and mixed well.
Place the liquid jello in your refrigerator for at least 2 hours, the longer the better, so that the jello can set firmly.
In a food processor, process the lemon Oreos until ground into a fine sand-like texture.
In a large bowl, combine the ground Oreos with the melted butter until a loose wet sand texture forms.
Press the lemon Oreo mixture into the bottom of a 9x13 tall-sided dish to form an even layer crust. Place the crust in your refrigerator for at least 2 hours to chill.
Once jello and crust are both firm, remove the jello from the containers by setting the containers in warm water until the edges are loose enough to slide out of the containers.
Cut the colored jello into 1-inch cubes and place them randomly over the lemon Oreo layer in your dish.
In a large bowl, stir the unflavored gelatin and 2 cups of water together for about 2 minutes or until the powder is dissolved and mixed well. Add the sweetened condensed milk and stir very well.
Pour your gelatin mixture over the colored jello and gently press the exposed jello down into the mixture until the top is fairly smooth. If some are sticking up, that is ok. Refrigerate this mixture for at least 2 hours or until well set.
Cut cubes using a warm knife and serve cold.