You should talk to her and tell her if she does not stop this obscene child abuse you will have her arrested and have the children taken away.
You may want to lock up the computer, or at least get it out of the bedroom. While it is not unusual or obscene for children that young to run around the house undressed, there is no reason for the children to be naked on camera while your wife is chatting with a man on the other end. Given the nature of the communication, it is possible to interpret her actions as sexually exploitative of the children. That would constitute child abuse. If you know about it and don't do anything to protect the children, you can also be a Respondent in an abuse proceeding. you must stop this practice.
If talking to her doesn't work, you may want to talk to a divorce lawyer. You say she is carrying on an online affair. She may be putting your children at risk. You may not need to get divorced, but you need to do something.
If I haven't understood the situation correctly, and you are already separated from your wife, you should obtain custody and/or seek to restrict her access. Of course, you will need to prove her actions to the court.
This anawer is not intended to create an attorney-client relationship and may be considered attorney advertising. This answer should not supplant advice received from any attorney the questioner may have or obtain, as that attorney will be able to provide more thorough and informed advice.
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