I would add to be blunt with the WS and state the obvious, since the obvious seems to go over their fogged-up, addled brains.
State these facts over and over again in the first month, to let them know the ideas going through their heads are nonsense:
1. You WILL have to choose one of us, and the clock is ticking. And that is because...
2. I will never accept a "don't ask, don't tell" marriage and am not as pathetic or immoral as she (the OW - or OM if the BS is the husband) is to be willing to share.
3. If you are waiting for me to calm down to be able to resume your affair and go deeper undercover, that won't happen. If your affair resumes, eventually I will find out because I am no longer naive about who you are or the level of deceit and dishonesty you can sink to.
4. Your actions will speak for your decisions even if your mouth never says them. If you keep seeing her, then your actions will have made the decision to divorce even if I become the first to fill out the paperwork. If you go around telling others that I kicked you out, then I will correct that misstatement to say that you dating OW left me no choice, and therefore, the decision to divorce was yours.
5. If we divorce, that's it.
I will not remain your best friend, fix your car, do your errands, or serve Thanksgiving dinner to you and the OP singing happy songs around the holiday table even for the sake of the children. Once you're gone, you are out of my life entirely except on a "need to know" basis about the kids' schedule, and preferably that can be done by e-mail.
6. If you walk out, then you you need to get a place for kids to visit you, since you will not be hanging around this house evenings and weekends, pretending to yourself that hanging around on a Saturday afternoon and mowing the lawn makes up for the fact you looked for a replacement for your spouse and found one.
7. You are either with her or you are not. There is no in-between: no e-mails, calls, lunches, dinners, coffee or kiss and grope sessions in parks or hotels or anyplace else with the OP.
A BS incredibly, mind-boggling callous that they actually believe a BS will step aside gracefully, will screw him occasionally for old times sakes (or to the female OW, she will expect to keep getting money and having car or household repairs done by BS.
The reason to say this stuff early is that most have the idea of going underground and keeping both.
And it NEVER hurts to let them know you have a Web group of formerly cheated-upon, or had loved ones cheated upon, to offer you support-group members to warn you should his actions appear to be an attempt to deceive you.
[This message edited by suspiciousmind at 10:11 AM, June 3rd (Sunday)]