Can someone catch me up please!!

I wana start watching the show butnit would be nice if someone caught me up! Pleasee the only thing I know is the main female lead turns blue, apprently?

Firstly welcome to the forum..the story is of a vishkanya aparajitha who was caged in her home,her family tells that she had rare disease that s y she can't go out,one fine day she met Malay mittal who unknowingly falls for appu,so as she but destiny had something else in store,when she comes to know about her real identity and how mittals family did wrong to her family... then she decides to take revenge on the culprits.

But now they are planning to make appu vamp and brought new girl for Malay...if you want to see a dark love story then better you don't start watching it or else you will get upset.. otherwise you can go for it,as some find new girl Nd Malay pair very good and refreshing

But what was the wrong thing  malayas family did? And what exactly is a vishkanya? Why is appu turning blue but her mom doenst?

Malayz dad had 2 wife's and one is appuz mother's sister,he cheated on two women,malayz mom mistakes appuz mother as the women her husband married and plans to kill her,because if that appuz mom becomes lifeless Nd living like a dead person on a wheelchair...
Vishkanya is someone with poison in her whole body.in history many kings had used these women to kill their enemies...if u physical get close to them.then you will die..in show they showed it as a hereditary telling appuz mom was one among them..but still i think appuz aunt made her to take revenge

And the one you are thinking as appuz mom was actually her mom's sister kalpana,main vamp who is the wife of malayz dad