Complex sentence: Will went home and spoke with Marlena and started to realized that he had feeling for Sonny, but when he came to see him he saw Brian, a friend of Sonny's, flirting with Sonny and was devastated.
Split into simpler sentences: Will went home and spoke with Marlena and started to realized that he had feelings for Sonny. However, when Will came to see Sonny he saw Brian, a friend of Sonny's, flirting with Sonny and was devastated.