Np5,
There are actually lots of children of infidelity on this site. Most of us are very outspoken betrayeds. There is zero doubt that infidelity seriously effects the children.
I'm glad you have offered counseling to your oldest. Her avoidance and denial is an extremely common way children cope with infidelity. Unfortunately, it's that very poor coping mechanism that will hurt them in the future.
Insist on several sessions, and get all the rest of the kids in too. Children hide and deny their feelings to protect the parents. It's not in any way malicious, but it's no less damaging.
When we bought our house, one of the things that attracted us were the number of trees on the property. Most newer homes have all vegetation ripped out and you have to start all over. Our house wasn't brand new but new enough to have a decent sized lot with trees.
A couple of years later many of the trees started dying. At first we came up with plausible explanations ourselves. Oh a deer rubbed that one, must have opened it to rot. That one must have not gotten enough water. Blah, blah, blah.
After 4-5 of them died we called an arborist and we learned about this epidemic of homeowners planting trees. Most plant them too deep. This eventually kills the tree, as does that all too common mound of mulch around the base, as it mimmicks being planted too deep.
Now when people plant them too deep, they look great. They seem great. Dropping leaves in the fall, sprouting new ones in the spring, growing seeds, fruit, or flowers, whatever that tree is expected to do.
However, the truth is, it's already struggling. Most people can't tell. On average, it takes 10 years before the tree will show obvious signs of there being a problem, and many times that can be too late to save it.
These homeowners who plant the trees too deep don't know it because the average person owns a home for about 7 years before they move. The trees still seem fine.
To a trained tree expert, they can tell that a tree is not the right size for it's age, that it has more disease or insect issues than it's suppose to have.
We were told that typically, that homeowner goes on and continues to plant trees too deeply. And people buy their old places, thinking all the trees are great.
Of course this only matters to people who care about trees in their yard. My point is, your children are these trees.
You know they have been exposed to something traumatic and damaging. I know they seem fine, and they will often express they are fine, but odds are they have stuff they need to address about the situation.
Don't wait until it's obvious they need support, that could be too late. Some children will never feel comfortable expressing their true feelings to their parents. Again, many times this is done to protect the parents they already know are hurting.
They don't want to be an additional burden. Be sure you don't treat it as such. Tell them they might have things they need to express about what has gone on, even if they didn't think they did. Set up the appointments, and take them as you would take them for any preventive treatment.
Take them for several sessions. Remember it takes time to feel out and trust a therapist. And children have to be sure the adult I safe before they will open up.
Maybe, maybe, they are all fine and have no concerns or things to express. But maybe, they have stuff that needs addressed, and if left unattended, will cause problems in their future. Why not be sure?