Complex sentence: Following his parents' split, his mother takes him away from Walford in April 1989 but Ali snatches him back in May, leading Sue to have a mental breakdown and being sectioned.
Split into simpler sentences: Following his parents' split, his mother takes him away from Walford in April 1989. The next month his father snatches him back from his mother, which culminates in Sue having a mental breakdown and being sectioned.