All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
First of all, we ask Allah Almighty to relieve your worries, make a way out to your difficulties, and spare you from anguish and worry. We recommend you to supplicate Allah as much as possible, especially the supplications that suit your condition, such as the supplication of the Prophet who said:
“The supplication of the distressed: “O Allah, it is Your Mercy that I hope for, so do not leave me in charge of my affairs even for a blink of an eye and rectify for me all of my affairs. None has the right to be worshipped except You.” [Ahmad and at-Tirmidhi]
We also recommend you to frequently and abundantly say the Adhar (remembrance of Allah and supplications of the Prophet), for it strengthens the heart and it reassures the soul. Allah Says (what means): {Those who have believed and whose hearts are assured by the remembrance of Allah. Unquestionably, by the remembrance of Allah hearts are assured.} [Quran 13:28]
You should be patient as patience is the best thing that entertains the Muslim when in afflictions. Patience expiates bad deeds and magnifies the reward. The Prophet said: “The believing male and the believing female continue to be afflicted in their own self, children, and wealth until one of them meets his/her Lord without a sin.” [At-Tirmithi]
You should be keen on giving advice to your sister and her husband with good words, and seek the help of those who can help you in this endeavor and seek to reconcile between you, as reconciliation is good, especially since you have a relationship by marriage, which is one of the great bonds.
If he owes you money, you have the right to demand it, and if he does not return it to you, you have the right to refer the matter to the competent authorities that study the issues and affairs of Muslims (in your country).
He has no right to reprimand you for not helping your sister in the housework. It is acceptable to advise you politely, but it is more appropriate that he leaves the matter between you and your sister. You should have an understanding between you and your sister, and you should help her in that as much as possible.
We should note that the sister's husband is a non-Mahram to her sister, so she must treat him as such, taking into account the Islamic conditions in her dealings with him, such as talking to him when needed only, in addition to the obligation of wearing Hijab and not being in seclusion with him, and so on.
For more benefit on supplications at times of distress and grief, please refer to Fatawa 343300, 418060, 88282, 13277, 213715, 265417 and 377509.
Allah knows best.