That's a dodgy issue, Oli. On the one hand, Michael definitely used Kay--to help with his legitimization with her WASP background, and to bear his children. You might argue that the miscarriage ended her usefulness to him. On the other hand, I think he did care for her, in his way. In the next scene after the one I cited, he sits with Mama and asks if it's possible to "lose your family."
Ntra la porta tua lu sangu � sparsu, E nun me mporta si ce muoru accisu... E s'iddu muoru e vaju mparadisu Si nun ce truovo a ttia, mancu ce trasu.