Shivin's mum!

Ok so because i have only started watching the show this week i don't understand a lot of things about this show. One of these things are shivin's family dynamic. Apparently someone on the thread said shivin's mother is not his dad's wife but a mistress and the other woman who is in the house who always insults shiv's mother is shiv's dad's actual legally wedded wife. WTH is this? I don't understand any of this. And does shiv's step-mother have her own children with shiv's dad? Plus why did that woman go sick at shiv's mum just for going outside the house?

Shivin's birth mother is his dad's mistress as she is not legally married to him. The other woman is his lawfully wedded wife and both the women live under the same roof. Everyone else thinks mrs. Raichand to be shivin's mom as they do not know of the existence of shivin's real mom. Also she shouted at shivin's mom to not go out as she doesn't want anyone to find out about shivin's mom. It would tarnish their image.