Complex sentence: He helped produce that album, as well as her next four, occasionally contributing his own musical compositions to which Mitchell would add lyrics; it was during the recording of "Turbulent Indigo", in 1994, that their marriage broke apart.
Split into simpler sentences: He helped produce that album, as well as her next four, occasionally contributing his own musical compositions to which Mitchell would add lyrics. It was during the recording of "Turbulent Indigo", in 1994, that their marriage broke apart.