Complex sentence: She married Richard Pearsall, an artist friend of her brother's, at 16 and lived for 8 years with him, travelling in Spain and living in Paris, before leaving him in Venice while he was sleeping without telling him anything.
Split into simpler sentences: She married Richard Pearsall, an artist friend of her brother's, at the age of 16. They were together for 8 years, travelling in Spain and living in Paris, when she left him in Venice while he was asleep, without telling him anything.