Now that I can think straight
So herpes you can work around to minimize the risk, lots of people have healthy active sex lives and never seem to infect other people.....because they are careful and don't ignore common sense when they are at risk. G can be cured, so patience is key. I don't know much about HPV. All that being said, this couple seems very at risk for even worse infections...the kind that kill. Your wife has got to see reason in your concerns. You have children right? How will they feel if their mommy and or daddy get AIDS?
If she goes ahead with this perhaps you should insist on having completely safe sex with her or even better...find yourself a low risk girlfriend and get those needs met elsewhere while she enjoys this couple.
Take care and be safe