Technically, it shouldnt be a burden on her, because the cleaning and washing for them is your duty, not the wife. She isnt required to cook, clean or laundry for you let alone your parents. So if there is even a small expectation from her, then you are in the wrong. She will however be responsible for the upkeep and care of her own ageing parents, so make surea you keep that in mind.
I dont have a problem with joint family, providing each family unit has their own living space and privacy and freedom to do their own thing without interference from others. And that doesnt just mean a separate bedroom, or three families holed up in one small house. That is simply ridiculous.
Islam emphasises on respect for parents; but equally emphasises on other things such as; kindness to the wife ( the best of you is the one who is kind to his wife) and protecting the sanctity of marriage, as a pillar of society.
A marriage that risks break down risks tearing apart the relations and unity of a large segment of a community. its affects are quite widespread, including on innocent children, and not just about the couple divorcing and going on their merry way. Hence divorce is the most disliked of the permitted acts.
So everything has to be done in order to protect that unit, even if it means providing a separate accommodation, or providing help for the household chores, its the least a man can do for his wife, as a means to restore or maintain harmony in the family.