I agree with others. The kids will have to be on their own, unless you feel there's abusive situations. I addressed some of these issues with the xH and he had to handle with his new W (this was 15 years ago). Kids are young men and relate with her okay, but I am their mom. Some things, unfortunately, have to work out on their own, depending on how long the R goes with the OW. A little advice: You're the mom and H is father and the OW doesn't even know the kids, but may want to relate at some time. She may not even want them around. I had this situation and that's difficult. Your H & OW may not last long and then you'll have to help kids through it wasn't their fault syndrome. Be the listening parent and have a lot of good parenting skills and talk with the children and give them a good example.