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 distress, make a way out to your difficultly, and protect you from the plots of the plotters, and the envy of those who envy you, as He is near and He answers the supplication.
We advise you to turn to Allah and seek his refuge; the benefit and harm are in His Hands, and the forelocks of the creation are in His Hands (i.e. He has total mastery over them). So have trust in Allah and rely upon Him, and remember the words of the Prophet of Allah, Hood, may Allah exalt his mention, as the Quran says on his tongue (what means): {So plot against me all together; then do not give me respite. Indeed, I have relied upon Allah, my Lord and your Lord. There is no creature but that He holds its forelock. Indeed, my Lord is on a path [that is] straight.} [Quran 11:55-56]
You have to be patient because patience is the door to much goodness –Allah willing.
For more benefit on the virtues of patience, please refer to Fatwa 83577.
This is in addition to observing the Athkaar (mention of Allah) as the hearts are assured by the remembrance of Allah, as Allah informed us in His Book.
One of the best Thikr in this context is what Allah said in the verse on the tongue of Prophet Jacob, {He said, “I only complain of my suffering and my grief to Allah.} [Quran 12:86]
The mother of the believers ‘Aa’ishah used to repeat this a lot when she was accused in her honor.
As regards your question about the punishment for the actions of these people, if you mean, by this, a specific worldly punishment, then the Sharee’ah did not determine a special punishment for this, but the person deserves that the ruler disciplines him in order to repel him from this heinous act.
If you mean, by this, a special punishment in the Hereafter, then there is also no specific punishment that is reported in this regard, but the person who does that is upon a grave danger and deserves a painful punishment, especially that his crime is related to the rights of the creation.
Allah Says (what means): {And those who harm believing men and believing women for [something] other than what they have earned have certainly born upon themselves a slander and manifest sin.} [Quran 33:58]
You have the right to plead your innocence; the prominent scholar Ibn as-Sa’di said in his Tafseer while listing the benefits of the story of Yusuf : “The person is not blamed for trying to refute the accusation from himself, and plead his innocence about it; rather, he is praised for doing so....” [End of quote]
Hence, you should sit with your husband and discuss with him about this matter in a good style; it may be that if he is convinced, he will help you in declaring your innocence in front of others. You may also seek the help of the wise and rational people whom you expect to have an influence so that they may try to reconcile and defend you in repelling these accusations; this is one of the best acts by which one gets closer to Allah.
If your in-laws (family of your husband) persist with these accusations, then threaten them to take the matter to the responsible authorities, as they may be deterred. It is really acceptable for you to take the matter to such authority if necessary, and if there is a benefit in doing so.
Allah knows best.