Imo, an "emotional affair" is worse than a physical one. One can argue for lust on the spur of the moment. But three years of emotional involvement is cheating your spouse of the focused attention they expect after a wedding ceremony bonds two people together.

My advice is one step further than parentalunit1: empty the bank accounts and take the cash to an undisclosed family member, who will hold said cash without putting it any accounts. Everything on paper is traceable.