Axl Rose's Ex-Wife Backs Him Up -- Axl Didn't Graffiti My House!

They're divorced, but Axl Rose's ex-wife still has the Guns 'N Roses singer's back -- insisting Axl NEVER tagged her house with vengeful graffiti ... and now, she's also going after the artist behind the allegations.Axl's ex Erin Everly just sent a…