This women urgently needs to consult a Doctor instead of a lawyer and suicide is not the way to get away from your fault.If you commit suicide then your poor husband and his parents will be put in jail under section 304B as the police and your family will make it suicide because of dowry.Thanks for our gender biased laws.
Now you say he lived with his girlfriend and then you say its like marriage and you also say you read and heard their conversations.How this is possible when his relationship already ended in 2010 ?
You cannot judge that he cheated his girlfriend as you mentioned that she had undergone 3 abortions that shows how irresponsible her girlfriend was in thie 21st century when one can easily find contraceptives.
Now you say your world has ended as husband is everything for you but here i see its more infatuation which you have for this man as he never loved you and you are after his love.I don't see here anyone cheated you as neither he loved you or promised you with anything and if you arranged marriage in 15 days without knowing him then i would say its your parents who cheated you and not the man and his family.
Also you said the biys parents knew everything and did not inform you before marriage,so be practical no parents really know what their adult son is doing and its you and your family who should have checked it and when you say he was in relation from 2002-2010 then this 8 yrs relation is not hidden in society and someone would be knowing which you should have checked before.
I would advice you please see a Doctor and get proper treatment and start a new life with someone who loves you and whom you can love instead of crying that he and his family destroyed your life.