I am more familiar with American Laws than Indian Laws so what I am writing might not fully apply in India.
(1) Adultery and Bigamy are totally different things. Adultery is not a crime BUT bigamy is a crime.(In USA)
(2) Aduletry Means having physical intimacy (s*x) with someone other than once legally married wife/husband.
(3) Bigamy means legally being married to two women simultaneously (at the same time)
Just having physical relations with someone other than his own wife is not bigamy..
Indian experts ..please explain this Indian context..Is it different under Indian Laws ?