Is the woman who sent nude pictures to a married man who then died, leading to her exposure, considered a transgressor upon whom God's wrath has descended? And is she obligated to seek forgiveness from his family and his wife, especially since she knows that God has made it easy for her to worship and to adhere to the matters of her religion?

It is not clear from your words that you wronged the man's wife or his family, for you to seek their forgiveness. If you have wronged them through backbiting or similar actions, then supplicate for their well-being. If they have wronged you, then forgiveness is better, or you may seek retribution from them on the Day of Judgment. Have a good opinion of Allah and forget the past. Know that they have acted wrongly by exposing you and sending pictures to your family, for it is obligatory to conceal the repentant Muslim.