Assalaamu alaykum. I got married six months ago. After two months of marriage, my wife started getting symptoms of dilated cardiomyopathy and went into treatment for four months until she died last month because of a pulmonary valve leak. We were very happy as a couple after our marriage and loved and respected each other a lot. My in-laws were also happy about it. Soon after my wife died, however, my in-laws forced me to give them all the jewellery and bridal gifts. I do not mind giving it , but as it belongs to my wife, do I have any authority over my wife's belongings? What does Sharia law say about it?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger. 

May Allaah console you in your grief, and we ask Him, Exalted is He, to confer His forgiveness and mercy upon her and render her among the dwellers of the highest Firdaws in Paradise.

If these jewelry and gifts belonged to your wife, as is stated in the question, then they are part of her estate and should be divided among her rightful heirs. It is impermissible to deny them their rights to their shares in them according to the Islamic inheritance laws. Allaah, The Exalted, says (what means): {For men is a share of what the parents and close relatives leave, and for women is a share of what the parents and close relatives leave, be it little or much - an obligatory share.} [Quran 4:7]

Moreover, Abu Hurayrah narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said, “If someone leaves behind some property, it is for his heirs.” [Al-Bukhari and Muslim]

Hence, you have a share in everything that your wife left, just like her other heirs; no heir has the right to take her belongings and exclude the other heirs.

Your share in your wife's estate is half of it; Allaah, The Exalted, says (what means): {And for you is half of what your wives leave if they have no child. But if they have a child, then for you is one fourth of what they leave, after any bequest they (may have) made or debt...} [Quran 4:12]

Allaah knows best.