Compare Cat. vii. 7.  The Jerusalem Editor observes that the expression “My God” is understood by the Fathers generally as spoken by Christ in reference to His human nature, but Cyril applies this, as well as the other expression “My Father,” to the Divine nature.  So Hilary (de Trinit. iv. 53):  “idcirco Deus ejus est, quia ex eo natus in Deum est.”  Compare Epiphanius (Hær. lxix. 55).