By marrying another person during the subsistence of your marriage is an act of bigamy and an offence under criminal law under the section 494 IPC.
The punishment for bigamy is imprisonment, which may extend till 7 years or fine or both. In case the person charged of bigamy has performed the second marriage by hiding the fact of first marriage, then he shall be punished with imprisonment of up to 10 years or fine or both.
Bigamy is a non-cognizable offence.
The period of separation shall never be a reason for a marriage to be automatically dissolved .
The dissolution of marriage can be made only by a decree of divorce by a court of law and there is no such system that since you both are living separately for years that your marriage can be dissolved automatically.
As per Hindu code, only the first wife is a legal heir of the husband while the second wife is not entitled to any share in the ancestral estate and, if the husband has died without leaving a will, even in his self-acquired property. Once the second marriage is declared null and void, the wife concerned cannot even claim maintenance as a matter of right.