Slow Cooker Rotel Chicken Spaghetti

• 2 Chicken breasts, boneless

• 1 10 ounce can Rotel diced tomatoes with green chilies, original or mild

• 1/2 cup Yellow onion

• 2 (10.75) ounce cans Cream of chicken soup

• 12 oz Spaghetti, cooked and drained

• 1 Salt and pepper

• 2 cups Mexican blend cheese

• 1/4 cup Chicken broth or water