Firstly, you shouldn’t directly go to a conclusion. Try to talk to your wife about this first, then only take any action. It may be possible that they were talking about something important and your wife isn’t cheating on you. But if you find out that she is cheating on you then this will be a case of adultery. 
Adultery is voluntary sexual intercourse between a married person and a person who is not their spouse. Adultery is extramarital sex that is considered objectionable on social, religious, moral, or legal grounds. As you said, your wife and your boss are having an affair, then she is clearly cheating on you.
Before 2018, Section 497 IPC criminalized adultery by imposing culpability on a man who engages in sexual intercourse with another person’s wife. Adultery was punishable with a maximum imprisonment of five years. Women, including consenting parties, were exempted from prosecution.
After much back-and-forth, the 2018 Supreme Court verdict decriminalized Section 497 of the IPC, which criminalized adultery and treated a woman only as her husband’s property, depriving her of the ability to make decisions.
Unfortunately, you can’t take any legal action against her based-on adultery but adultery is still a valid ground for divorce. Before thinking of anything mentioned above, I would suggest you to have a proper communication with your wife and your boss and then take any action.
We would suggest you not to quit your job immediately. If possible talk to your boss about this and ask for an explanation.
And if you want to separate, then you can opt for divorce later from your wife.