Taubah and Repentance

Q: 'If you start it with haram, it can never be blessed' Is it true? Is it true that the marriage can not last long if it was started in a haram way like sex before marriage? How do I make it work after marriage?

Q: I am an 18 year old student and a practising Muslimah. But I committed a sin few days ago. I got distracted to a sexual website and made a chat. The guys asked me for pictures of the chest and I gave it. After sending it I realised how big sin I committed. I felt very bad and cried for forgiveness. Because I want Allah to trust me again and I can be pure again. I never did anything like this. But now I feel that I'm not a good person. Will Allah Ta'ala forgive me? I promised myself not to go this way ever. I dont want Allah or my parents to be ashamed on the Day of Judgement in front of Shaytan. I had a dream of making them proud. What should I do to get away from the punishment? I am scared of Allah.

Q: A muslim unmarried girl has affairs with multiple hindu boys for several years secretly and her family is not aware. Now her family is getting her married to a muslim boy. She says that she has realized now that she did wrong and would like to do Tawbah. Can she repent now? Will her repentance be accepted? And now how can she repent?

Q: If you commit a sin then repent, is that enough to get forgiven by Allah or I also need to do good deeds additional to my repentance?

Q: Can we as Muslims repent for even the most heinous sins? I mean anything!!! Any serious sin can be forgiven through true repentance? The word any is important here, it covers any/all/every sin a human being can commit!!! Or is there any limitations to Allah's mercy!

Q:

1. If someone had unlawful acts/relations more than one time/many times, with his married paternal aunt (father's sister) and then with the same paternal aunts' daughter in law (son's wife). Also with same paternal aunt's daughter. His actions were such that perhaps hurmat maybe established, meaning anything but not actual zina. He is a single adult and lives away from them. What is the status of the marriages of his marries parental aunt, the same aunt's daughter in law and the same aunt's daughter? He has asked someone, and being told all of them's marriages are still valid.

2. Also, how to repent in this case? Mufti Taqi Usmani says, you can seek forgiveness from Allah Ta'ala by making sincere repentance, then you should have hope and forget your past sins, trust Allah's mercy... Allah's mercy is so vast, he can and does forgive any sin, no matter what.

Q: I want to ask, if a boy had intercourse with his sister but he was not doing it intentionally with his sister. He also had intercourse with his girlfriends, will he be forgiven?

Q: A person commits kabeera gunah then he repents and it is forgiven by Allah and it's removed by the angels but although it has been removed, will he get punished for that sin though it has been forgiven?

Q: What is the way forward for one who makes taubah and regrets a sin, yet keeps falling back into it?

Q: How do I know if I have forgiven someone? I had slept forgiving someone but after waking up, I again felt bad about that person, though I didn't have any bad feeling or hatred that night.