In a large mixing bowl, combine the cooked pasta, sautéed garlic with olive oil, 1 cup ricotta cheese, 1 cup shredded mozzarella, 1/2 cup grated Parmesan, cooked crab meat, cooked shrimp, chopped fresh parsley, 1/2 tsp red pepper flakes, 1 tsp lemon juice, salt, and pepper to taste. Gently fold everything together until well combined and evenly coated.