Complex sentence: Separated from her husband, from a relationship with magazine editor Ernest Walsh, she had had a daughter but in 1928 she met Laurence Vail, who was then married to Peggy Guggenheim.
Split into simpler sentences: Separated from her husband, she formed a relationship with magazine editor Ernest Walsh with whom she had a daughter. In 1928 she met Laurence Vail, who was then married to Peggy Guggenheim.