Remind yourself (constantly) that their horrible behavior is their problem, not yours.
Don't get sucked into their endless series of melodramas.
Limit your interactions with them as much as is humanly possible.
Always keep your cool and maintain your composure when dealing with them. (They will likely try to get you just as worked up and upset as they tend to get. After all, as we all know, "misery loves company;" so don't fall into their emotional traps.)
At the workplace, you are compelled to socialize with them, at least on a minimal basis, but if they try to get you to socialize with them outside of the workplace, do not accept any of their invitations.
Use a tone of voice that is not cold or cruel, but that does send the message that you intend to keep your emotional distance.
Once they see that they cannot easily engage you or rile you up, the emotional vampires in your midst will likely figure out that you have already "got their number"; and chances are that they will give up and stop targeting you for emotional harassment.
