Did you bf tell you he is leaving her or is it already in the works? 90% of the time, the husband never leaves the wife, and will just string along the mistress as long as possible.When the mistress is gone he finds another and does the same thing to her, telling her he is leaving soon....but "the kids" and this and that.
If she finds out about it, yes she can bring it up in a court and he will get nothing. She will automatically get custody of any children they have together, she may also request whatever she wants for visitation and he better pray he gets a judge who's never been cheated on, because I don't care who it is, a judge will do whatever they want to someone they just don't like, within the legal limit of the law.
Also, I don't know for sure about North Carolina, but in some states, the wife can actually sue the mistress for the break up of the marriage, for financial compensation.
Yeah what Dwain said "Alien of Affection" she could sue you for that.