Ro*tel Chicken Spaghetti

3 cups cooked chicken, cubed
1 (7 to 8 ounce) package spaghetti
1 large bell pepper, chopped
1 large onion, chopped
2 celery stalks, chopped
8 ounces sliced mushrooms
1/4 cup butter
1 (10 ounce) can Ro*tel diced tomatoes and chilies
1 or 2 tablespoons Worcestershire sauce
1 pound Cheddar cheese, grated (or can use Velveeta)

Cook and season chicken, then de-bone when cool. Save 1 1/2 quarts broth.

Cook spaghetti in broth; drain, but do not rinse.

In Dutch oven saut