Okaythen:
I see nothing wrong with someone using the computer while they are at home. Being a single mother is very hard work, not to mention stressfull, if chatting with people on the internet is a hobby Shari has, then so what. It may even be good to relieve some of the stress she may be experiencing.
My mother raised me and my sister alone, thanks to the W.T.S teaching at the time of scriptural freedom, she was not able to remarry when we were young. She was so depressed, There were times when she was physically abusive, verbally abusive, or pased out from (God knows what drug). When we were babies, if it wasnt for my grandmother, we wouldnt have even been fed. I dont hate my mother but I would never do that to my children. I actually use it as an example of what I would not want to become.
If a child is in an abusive situation, the adult seeing this, should call Child Protective Services.
If your main concern is the children and you honestly thought they were being abused, as responsible as you seem to think you are, Im sure you would have called right away.
It seems to me from your actions, you may have had other motives and what you were trying to acomplish was to humiliate or hurt Shari.