Steamed Mussels in Tomato Sauce

Name: Steamed Mussels in Tomato Sauce
Ingredients: 4 strips bacon, chopped; 1/2 small white onion, chopped; 3 cloves garlic, sliced; 1/2 teaspoon red pepper flakes; 1/4 teaspoon salt; 1/4 teaspoon black pepper; 1/2 cup white wine, optional; 3 to 4 cups marinara sauce , store-bought or homemade; 1 1/2 to 2 pounds mussels , scrubbed, debearded, rinsed and drained; 1 pound spaghetti, drained, if serving as a main course; Crusty bread , if serving as an appetizer; Fresh parsley