Complex sentence: Abe spends his last minutes trying to convince Sherry she must kill herself before her own possession is complete however by the time she reaches for the gun the police pick it up and get her into an ambulance.
Split into simpler sentences: Abe spends his last minutes trying to convince Sherry she must kill herself before her own possession is complete. However, as she reaches for the gun the police pick it up and she is put into an ambulance.