Classic narcissism with sociopathic tendencies. I'm my experience, they'll let you go when they are good and ready, which could br between the next day and never. Depending on their level of narcissism, your best bet is to run away. Leave everything and get the hell outta dodge.
I still don't get it, is it like seeing their victims in pain gets them high? Do they want to tie the other person to themselves so that they can play with them when they are bored even when they have no intentions of commitment or loving the other person. Cheating is a conscious choice. Why even get into a relationship if that what you're going to do? Or why not just break up with your partner, Why cheat?
Why do cheaters always refuse to divorce!? Why do they expect their partner to stay with them after cheating on them!? How does their brain even work!? Do they even have brain!?