I have to disagree. The Blues can be uplifting / good times music.
Oh, I agree, flickster. Blues lyrics can be funny as hell. ("Nobody loves me but my mama, but she could be jiving, too.) But I also agree with the insight of music legend Bleeding Gums Murphy when he told Lisa Simpson, “The Blues is about making a lot of other people feel bad, and making money while you’re at it.”
My sister-in-law. (unfortunately, I’m not kidding!:()
The proper term, I think, is “psychic vampire”.
epicaricacy?
(supposed English version of Schadenfreude)
Another vote for misanthrope. It means exactly what the OP says, and is essentially just the old-fashioned way of saying ‘misery guts’.
No, as that means “taking pleasure in another’s misfortune”. The OP seems to want someone who is themselves miserable, and who wants to spread that feeling.
No, it doesn’t. It means “a person who hates or distrusts mankind”, and carries no implication of misery on either side.
How about a bit of lateral thinking, folks. What’s a term for the opposite, someone who is happy and wants others to be happy? Pollyanna? If so the opposite might be monoanna.
Pollyanna’s literary opposite is Scrooge.
Heh. I wonder how many Dopers are old enough to remember “nattering nabobs of negativity”? 
Spiro Agnew.(and how many WHO’s are being uttered?)
When he actually said that…with a straight face mind you…how many WHAT’s were uttered? Fun guy, that Spiro.