Upon learning that Macduff has traveled to England, Macbeth responds by having Macduff's wife and children assassinated.What does Macbeth achieve by doing this?What does it suggest about him?

Macbeth does not achieve much other than showing himself to be a bloodthirsty tyrant and giving Macduff a reason to cut off his head. The slaughter shows the extent of Macbeth's paranoia and disregard for life. By this point in the play Macbeth has bought his one-way ticket to being a complete sociopath. There is no turning back for Macbeth.

I am in blood/Stepp'd in so far that, should I wade no more,/Returning were as tedious as go o'er.