Its true karma is a bitch and also MA baap K karmo ki saza bacho ko bhugatni hoti hai. From what we have seen till now about Maya's past its clear that Maya has a logical and valid reason to revenge Roy family. She killed Rishi because she lost her own child. Roy's killed her child so she killed their child. Jan ke badle Jan, bachcha ke badle bachcha cheen Lia.
Now I am waiting for Manas part of story. What happened to him in the past.