Complex sentence: When Cooper talks to him BOB is gone, and Leland dies next to Cooper, but the last thing Leland says, is that he regrets his actions and tells Cooper that he did not want to harm Laura, but that BOB made him do it.
Split into simpler sentences: When Cooper talks to him BOB is gone, and Leland dies next to Cooper. Before he dies, Leland says that he regrets his actions, and he tells Cooper that he did not want to harm Laura, but that BOB made him do it.