Can I Nikkah someone whom i love without anybody knowing

I Love a person who already has a wife (his wife also knows that) and he loves me too.we want to get married after telling his wife about it.but we cant inform this to our parents.because we both know that this relation is impossible to accept by them.we tried to stop this relation.we tried to not talk to each other.but our love is grown stronger even without seeing or talking,then we realise we cant separate .But we dont want our relation to go in a haram.So we really want to make our relation halal.even its for sometime or whatever.we want to live in a halal way.just like an islamic couple