She admitted to zina and is going to get married, and is afraid of being exposed to shame
Question

There is a girl who got to know a young man and he promised to marry her, then he took her honour and made a video of her. Now she is suffering because of sin and shame, and she is going to get married soon to another man, who does not know what happened to her with regard to her honour. She is afraid of being exposed to scandal before him and her family. What should she do?.
Praise be to Allah.The calamity asked about here is one of the outcomes of haraam relationships: making acquaintances, promises, lies, love and infatuation, followed by immoral actions, ruined lives, disgrace, scandal and shame. Sincere advisers are still shouting at the heedless to wake up and telling the deluded to pay attention, whilst the proponents of free mixing and evil are still defending their stance, claiming that there is nothing wrong with these relationships, and that it is not necessary to impose restrictions on boys and girls. The one who will suffer as a result of this sin and because of the scandal, worries and anxiety is this deceived girl, who followed the footsteps of the Shaytaan and was fooled by wishes and false promises, so she went against the command of her Lord to stay in her house, lower her gaze, avoid speaking softly and adhere to hijab. Verily to Allah we belong and to Him we will return. Hoe regrettable it is for the Muslims that this corruption exists in their societies and has crept into their houses, with the neglect of fathers and mothers, brothers and sisters. 
How abhorrent is zina and how awful its consequences in this world and in the Hereafter. Hence the punishment for the one who does it is either flogging or stoning, along with the painful punishment in the fire of Hell. 
Allah, may He be exalted, says (interpretation of the meaning):
“The woman and the man guilty of illegal sexual intercourse, flog each of them with a hundred stripes. Let not pity withhold you in their case, in a punishment prescribed by Allah, if you believe in Allah and the Last Day. And let a party of the believers witness their punishment.” [an-Noor 24:2]
“And come not near to the unlawful sexual intercourse. Verily, it is a Fahishah (i.e. anything that transgresses its limits (a great sin)), and an evil way (that leads one to Hell unless Allah forgives him)” [al-Isra’ 17:32].
In the hadeeth of the dream that the Prophet (blessings and peace of Allah be upon him) saw, he said: “…So we went on, and came to something like a tannoor (a kind of oven, lined with clay, usually used for baking bread).  – I think he said: In it there was much noise and voices. – We  looked into it and saw naked men and  women. A flame of fire was reaching them from underneath, and when it reached them, they cried out loudly. I asked them, ‘Who are these?’ They said to me, ‘Move on, move on!’ … I said to them, ‘I have seen many wonders this night. What do all these things mean that I have seen?’ They said: ‘We will tell you. … The naked men and women whom you saw in a structure that resembled an oven are the adulterers and adulteresses.’”
Narrated by al-Bukhaari in Baab Ithm az-Zunaat, no. 7047 
Hence what this girl has to do is repent sincerely to Allah, may He be exalted, regret it a great deal, pray for forgiveness, and resolve never to do such a thing again, in the hope that Allah may forgive her and pardon her. She should also offer a great deal of supplication (du‘aa’) and beseech Allah, may He be exalted, to conceal her and not expose her in this world or in the Hereafter, and to suffice her against the evil of that evildoer. She should choose the times when supplications are answered, such as the last third of the night, the time between the adhaan and iqaamah, and the last hour of Friday. She should also do a lot of acts of worship, especially praying and giving charity. And she should think positively of her Lord, may He be glorified, because He said in the hadeeth qudsi: “I am as My slave thinks I am, and I am with him when he remembers Me. If he remembers me to himself, I remember him to Myself; if he remembers Me in a gathering, I remember him in a gathering better than it; if he draws near to Me a handspan, I draw near to him an arm’s length; if he draws near to me an arm’s length, I draw near to him a fathom’s length; if he comes to Me walking, I go to him at speed.”
Narrated by al-Bukhaari, 7405; Muslim, 2675 
Ahmad (17020) narrated from Waathilah that the Prophet (blessings and peace of Allah be upon him) said: “Allah, may He be glorified and exalted, said: ‘I am as My slave thinks I am, so let him think of Me however he wishes.’” Classed as saheeh by Shu ‘ayb al-Arna’oot in Tahqeeq al-Musnad. So let her think positively of her Lord, may He be glorified, and think that He will conceal her and suffice her, and accept her repentance and put her affairs straight. 
She should understand that she has to conceal herself and not tell anyone about her sin, neither her husband nor anyone else; rather she should conceal that even if he asks her, and she should employ double entendres. The hymen may be broken as a result of heavy menstruation, jumping or other causes. 
If it so happens that someone knows what happened to her, he should strive to conceal her first of all, then help her in her trial and try to get hold of the video recorded by that evildoer by reminding him of the punishment of Allah, may He be exalted, and the severity of the crime that he has committed. If he is able to use threats with him and call upon the authority of someone trustworthy who has any authority over him, in order to scare him, that is good. 
We ask Allah to accept our repentance and that of the believers, and to conceal our faults and protect us from worries and anxiety. 
And Allah knows best.