His wife claims that she was raped
Question

                I am a Muslim immigrant in North America. 18 years ago I was newly married and had to go out of town for business. My wife told me that during my absence someone got into the house and just kissed her, but then left, telling her that she is too young. But now after 18 years of our marriage she is telling me that yes she was raped by him. The man had sexual intercourse with her several times that day. During the last intercourse she could not hold back and had orgasm several times from him and hugged and kissed him 
Since the man was a rapist he never came back afraid of getting caught. I feel devastated from this incidence and very upset that why she did not tell me 18 years ago. I was kept in the dark for so many years, under the impression that no one has ever touched her. Please reply me ASAP what should I do? Is our marriage still valid? Should I divorce her? I also don't feel like going to the mosque and pray to Allah anymore. Please email me your reply ASAP to XXXX. Another point is that from the start when the man got into the house, she did whatever the man told her to do, she did not resist or scare him, or made him realize that it is a crime he is comitting, etc. She also did not scare him that my brother who used to live with us, is going to come in the house anytime. Her excuse is that she was too scared. I will wait for your advice.
Praise be to Allah.If what 
          your wife has recently told you is what really happened, then she has 
          committed a major sin and an act of clear betrayal by giving in to this 
          attacker and not trying to escape or stop him or call for help and so 
          on.  Her claim that she was forced to do it is not acceptable, 
          because she makes no mention of being threatened with a weapon or being 
          tied up, etc.  If this is indeed the case, and she clearly did 
          not try to defend herself, then what should you do and how should you 
          regard her?  
There 
          is no doubt that you should warn her and remind her about Allaah and 
          the Last Day and its horrors, and explain to her the seriousness of 
          overstepping the limits set by Allaah and betraying one’s spouse. You 
          should also remind her of the terrible punishment dictated by sharee’ah 
          for the married person who commits adultery, which is stoning to death.  
          
After 
          warning her in this fashion, if you see that she regrets what she did 
          and is striving to be righteous, there is nothing wrong with staying 
          with her, and your marriage will still be valid.  It seems most 
          likely that this woman is indeed sorry for what she did and has repented, 
          because she is the one who has brought up the subject after it had been 
          forgotten, and she has told you about it. Perhaps this is because of 
          her guilty conscience and sincere desire to seek forgiveness from her 
          husband.  The sin that she committed when she was very young and 
          living in the ignorant environment of America, and where she may have 
          resisted at the beginning of the attack, then softened, is nothing like 
          the sin of a woman who goes out of her way to commit it, and plans to 
          do it deliberately. Our advice is that if this woman is now righteous 
          and truly regrets what she did, then you should forgive her, especially 
          as you may by now have children who will suffer if you divorce her.  
          At the same time, you should continue to teach her, keep an eye on her 
          and not stay away from her for too long.  We ask Allaah to acceptance 
          repentance from us all.
 Finally, 
          I want to address a serious matter that you refer to in the second part 
          of your question, which is the fact that you say you no longer want 
          to go to the mosque or pray or make du’aa’, because of the crisis that 
          you are facing.  This is very strange, for whenever the Prophet 
           (peace and blessings of Allaah 
          be upon him) was faced with a serious matter he would turn to prayer 
          and ask Allaah to help him, and he taught us to do likewise. We should 
          not turn away from the houses of Allaah (mosques) or stop praying and 
          making du’aa’. Where else can you turn in times of trouble and who else 
          can you ask for protection in this crisis? Turn back to Allaah, my brother, 
          ask Him to relieve your distress and seek His help with patience and 
          prayer, for Allaah is with those who are patient.