So basically Envy is Jealousy, it's sometimes represented by a snake...
This bring to the idea of a shapeshifter "reptilian-like chameleon" that can take steal identities and abilities, why not some money too ha ! Envy is also portrayed as an Eye that can't stop looking at things and most importantly at YOU, so why not a sly tricky demoness with a bitter and soured personality, a truly calculated verbal woman who can't stop spitting her poison at you? With snake-like features and not like
she will remain mainly humanoid, and she can thieve you, take your identity, make you're existence obsolete while she's walking with your body envelope and will mock you in a very derisive way.
Some combat skills are welcome, but I can see her as a ranged demon who wields two sharp snake-like whips, she just can't stop lashing at you until you're just a piece of meat and will walk away laughing and spitting her poison at you, with verbal attacks and mockeries, a truly savage demon that can attack you personally and make you feel miserable...
Talking about snakes, and demons, I can't stop thinking of this picture :
http://www.spiritofthescripture.com/wp-content/uploads/2013/10/5994318261_0a9296d1df_b.jpg
This is basically... Eve... yeah.. Turning away God's commandment to not touch the fruit of knowledge, but she was tempted by the Serpent in Eden itself ! So.. Temptation, is having desires. It could be really funny in a way !
So after this inspiration, I was thinking about a woman who can control you, and make you tempted by things, not just by her, but she can make you force to have desires towards something or someone, a manipulative kind of woman that can control you're mind and body with only her powerful words. So basically she's bewitching you, just like Satan did with Eve in the Genesis.
Even if I like your ideas, I don't see how a demon will look for a "social" class and interactions with humans, only if its not for feeding their thirst of human emotions. So the "wife" thing, is basically.. not correct, because this is a trait of
who only seeks beauty and youthness and betrayed her husband for a higher social class, human society for a demon ? They don't care much about it !
If you look for a succubus or femme-fatale demon, you should distinguish her from others like :
or 
For more exotism, let's put a third eye on her forehead, and no, those ideas are not sponsored by reptilians !