Why does Macbeth blame himself for the death of his family?
Lady Macbeth is Macbeth's only family in the play, and she dies in Act V, scene v. Macbeth is in the middle of putting down a rebellion led by Macduff and Malcolm at this moment, and he barely takes the time to acknowledge the news from Seyton that she is dead. So, I would say that Macbeth, in fact, does not blame himself for her death. His only concern is winning the battle and retaining his kingship.
This lack of feeling or consideration of the feelings or deaths of others is an important thing to note about Macbeth by Act V in this play, for it is part of his journey as the tragic hero. He has transformed from a brave warrior with a conscience, into an emotionless killing machine who considers life to be a joke without meaning. He has, just after Lady Macbeth's death is announced, one of the most famous speeches in all of Shakespeare:
She should have died hereafter;
There would have been a time for such a word.
Tomorrow, and tomorrow, and tomorrow
Creeps in this petty pace from day to day
To the last syllable of recorded time;
And all our yesterdays have lighted fools
The way to dusty death. 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. It is a tale
Told by an idiot, full of sound and fury,
This speech is spoken at the culminating moment of Macbeth's sacrifice of everything he has respected, loved and honored in the name of ambition. So, no, I would emphatically say that he does not, in Act V, spend one moment in the sort of self-reflection that would cause him to blame himself for the death of his wife. Life, he concludes in the above speech, "is a tale/Told by an idiot, full of sound and fury/Signifying nothing."