Dont wear a cardigan, the sleeves are wide and that will just ruin the dress cause then its gonna look supper baggy. But if you still want it then get black it will match or if you could find a white and purple stripe cardigan. But get a necklace to match the dress with a bracelet or a waist belt if you dont want it look too dull.
__________________
" The oldest and strongest emotion of mankind is fear"
- H. P. Lovecraft