Remove casings from sausage, and discard. Brown sausage, bell pepper, onion, and garlic in a large skillet over medium-high heat, stirring until sausage crumbles and is no longer pink and vegetables are tender. Drain.
Stir in spaghetti sauce, next 3 ingredients, and, if desired, vinegar. Cook, stirring often, until cream cheese melts and mixture is thoroughly heated. Serve over hot pasta.