Complex sentence: Toby becomes deeply attached to Mrs. Lovett, thinking of her as a surrogate mother; when he discovers that Todd have been killing customers for Mrs. Lovett to bake into meat pies, however, he goes insane with horror and shock.
Split into simpler sentences: Toby becomes deeply attached to Mrs. Lovett, thinking of her as a surrogate mother. When he discovers that Todd has been killing customers for Mrs. Lovett to bake into meat pies, however, he goes insane with horror and shock.