What is the ruling on describing what the questioner and her sisters are experiencing in terms of marital and family problems? Is it a test (fitnah) or a trial (ibtila') or a purification (tamhees) for each of them? And who among them is in the right? And is the sisters' attack on her a test (fitnah) for her?

You are correct regarding the issues you mentioned between yourself and your two sisters. However, your disapproval of them should be expressed gently. Continue to advise them with kindness, affection, and good admonition. Avoid harshness and severity in inviting them, for Allah the Almighty says: ﴿Invite to the way of your Lord with wisdom and good admonition, and argue with them in the best manner.﴾ Vary your methods of advice, and use stories, encouragement, deterrence, and rational arguments. Be patient and strive in supplicating for their guidance. Your patience and effort will be in the balance of your good deeds, and for Allah to guide one person through you is better for you than red camels.