Complex sentence: Sally Mugabe was a trained teacher who asserted her position as an independent political activist and campaigner who was seen as Mugabe's closest friend and adviser, and some critics suggest that Mugabe began to misrule Zimbabwe after her death.
Split into simpler sentences: Sally Mugabe was a trained teacher who asserted her position as an independent political activist and campaigner. She was seen as Mugabe's closest friend and adviser, and some critics suggest that Mugabe began to misrule Zimbabwe after her death.