My thoughts on the backstory
Note: The following is pure speculation. I haven't read any spoilers that aren't already being mentioned nor have I seen the previous version of this novela.
Carlota is actually only a half-sister to Macarena and Javier. Either she is from their father's previous marriage or the result of an adulterous relationship. Javier, as the first-born (and ultimately the only) male child, was favored in terms of inheritance and education; their father assumed that Carlota and Macarena would eventually marry within their social class.
About ten years prior to the opening scene of the prologue, Cristobal briefly courted Carlota before realizing that he preferred Macarena. One night they gave in to temptation, resulting in Macarena becoming pregnant. The night this came to light, the father died, either a tragic coincidence or provoked by Carlota. Carlota siezed the opportunity to blame Macarena for his death, then sent her far away before her pregnancy began to show. She then told Cristobal that Macarena committed suicide and he left for Mexico City.
Their father's will gave generous trust funds to Carlota and Macarena as well as the family home, but left his remaining assets (possibly including a family business) to Javier.
Javier and Sagrario were married around this time (it had already been planned) and moved into their own house. A few months after they returned from their honeymoon, Macarena gave birth to a baby girl. Carlota tried to get rid of the baby, but Macarena -- with the help of a priest or a madre superiora -- arranged for her to be adopted by Javier and Sagrario. When she returned to the family home, she was told that Cristobal committed suicide just after the last time they saw each other.
Since this time Carlota has controlled Macarena with guilt while showing her best face to Javier, just as she had done previously with their father. She hated Sagrario from the beginning because Sagrario saw through her and because she "took Javier away" from her. She has hated Paloma from birth because she is a child of love... and of the man her sister "stole" from her. Also because Paloma was loved by her parents.
This is the only logical explanation I can come up with for why Carlota has such an irrational hatred of Paloma.
Anyone have anything to add to this?
The Fabio Principle: Puffy shirts look best on men who look even better without them.