What is Macduff’s opinion on grief? What action does he decide to take?

Macduff decides to take revenge. Then he says the following;

I shall do so; (take revenge)

But I must also feel it as a man:

I cannot but remember such things were,

That were most precious to me. Did heaven look on,

And would not take their part? Sinful Macduff,

They were all struck for thee! naught that I am,

Not for their own demerits, but for mine,

Fell slaughter on their souls. Heaven rest them now!