Complex sentence: His first wife and queen was his half-sister Kawalu of Oahu, his second his niece Kaapuwai Kapuaamoku of Kōloa, and finally the queen regent Kaahumanu (1768--1832), Kamehameha's widow.
Split into simpler sentences: His first wife and queen was his half-sister Kawalu of Oahu. His second wife was his niece Kaapuwai Kapuaamoku of Kōloa, and finally the queen regent Kaahumanu (1768--1832), Kamehameha's widow.