The fact is that a crime has been committed agaisn't the husband. Whether it was an abusive relationship or spousal abuse is a total different and separate case. Which shall be dealt in another trial. For now the woman (whatever her reasons maybe) is guilty of throwing boiling oil at the husband. She's guilty for committing the act.
However, as I mention earlier if there has been a history of abuse committed from her husband then a different trial must be made. Even thought both cases are related the criminal act is different.
The only thing that could link both cases is if the woman threw the oil at the husband in a form of self defense. If the investigators can connect that possiblity then the case should be trial as one.