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 is His Slave and Messenger.
If the matter is based on mere suspicions and not certain facts, then you have no right to harbor doubts against your husband. Allaah, The Exalted, says (what means): {O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin...} [Quran 49:12] If your husband denied, then, in principle, he is to be considered truthful and you should believe him until proven otherwise. For more benefit, please refer to Fatwa 133309.
Accordingly, if what you are experiencing are mere illusions and obsessive whisperings, then we advise you to discard them, lest this would ruin your relationship with your husband and incur undesirable consequences. You should not allow yourself to indulge in such doubts and whisperings and you should not yield to the urge to investigate the issue any further. Instead, you should express gratitude to your Lord that He blessed you with the grace of performing Hajj that year, for such good deeds are what genuinely matter, whereas the fleeting worldly affairs should not be given such undue weight. Allaah, The Exalted, says (what means):
· {Whatever you have will end, but what Allaah has is lasting. And We will surely give those who were patient their reward according to the best of what they used to do.} [Quran 16:96]
· {...Say, The enjoyment of this world is little, and the Hereafter is better for he who fears Allaah. And injustice will not be done to you, [even] as much as a thread [inside a date seed]."} [Quran 4:77]
Generally speaking, it is not the right of a husband to allow his wife to use the personal belongings of his other wife without her permission. The Prophet, sallallaahu ‘alayhi wa sallam, said: “A Muslim's property is not lawful (for another Muslim) without the former's own free will.” [Ahmad]
In this case, it is incumbent on your husband to turn to Allaah, The Exalted, in repentance from that sin and seek your pardon for what he did. Verily, forgiveness has great virtues. We have cited some religious texts highlighting the great virtues of forgiveness in Fatwa 84351.
Allaah Knows best.