When Macbeth is informed of his wife's death, he states, "She should have died hereafter./There would have been a time for such a word." (5.5.20-21). He is plainly indifferent to her death, though there are two possible interpretations of his comment.
One meaning could be that she should have waited and committed suicide at a later, more propitious time, when it would have a more telling effect. Now, amidst all the deaths, it becomes meaningless.
Another interpretation could be a simple, callous, "Well, I suppose she had to die sometime."
At this point, Macbeth has despaired to the point of seeing life as worthless. Each moment is an effort ("Tomorrow and tomorrow and tomorrow/Creeps in this petty pace from day to day/To the last syllable of recorded time"--5.5.22-24). His entire life has been without significance ("And all our yesterdays have lighted fools/The way to dusty death." --5.5.25-26). He sees no point in continuing, and there is nothing shameful about his wife's suicide ("Out, out, brief candle!/Life's but a walking shadow, a poor player/That struts and frets his hour upon the stage/And then is heard no more." --5.5.26-29). Not only his own life, but life in general, is a "tale/Told by an idiot, full of sound and fury,/Signifying nothing." --5.5.29-31