Preheat oven to 350 degrees. Spray a 9 X 13-inch baking dish with nonstick cooking spray. Line baking dish with parchment paper with the long sides extending 2-3 inches. Spray parchment with nonstick cooking spray.
Using a stand up electric mixer, beat butter until creamy. Slowly add sugar then continue to beat 4-5 minutes until it's fluffy. Add eggs one at a time, and beat after each addition until they're incorporated. Add lemon juice and vanilla and mix in.
In a small bowl combine flour, strawberry jello, baking soda, and salt. Add the flour mixture to butter mixture alternating with the buttermilk, beginning and ending with the flour mixture, mixing until just combined. Gently stir in strawberries. Pour batter into prepared baking pan and bake in preheated oven for 30-40 minutes or until a toothpick inserted in the center of the cake comes out clean. Cool cake completely. Lift the cake out of the pan, using the parchment paper extensions.
Make the frosting: In a large bowl, beat the cream cheese with 1/3 cup of sugar until mixture is smooth. Fold in strawberries.
In a large bowl, beat the cream and lemon juice until mixture is frothy. Continue beating on medium-high speed and gradually add the remaining 1/3 cup sugar. Beat until mixture forms stiff peaks. Fold half of the whipped cream mixture into the cream cheese mixture until just incorporated. Fold in the rest of the whipped cream mixture.
Immediately spread the top and sides of the cake with frosting. Serve :)