I think that one of Vito's strengths was the ability to separate personal feelings from business
He surely was aware that betrayal was part and parcel of the Business he had chosen.
He probably was disappointed that either Clem or Tess would turn on him,but wouldn't let it affect his course of action.
Michael made a couple references to things that Vito had probably taught him.
1) Keep your friends close,but your enemies closer.
2) Never hate your enemy,it clouds your judgement.