dsh,

This must be an extremely difficult situation to deal with. Seeing your son-in-law neglect your daughter and his child for a video game while you're supporting them. You have the added invasion of your privacy of having him in the family room at all times. I cannot even express how much that would irritate me.

If your SIL will not respect your wishes and give you some peace in your own family room, turn off the internet or install parental controls that will limit the hours he has access to the internet.

His grooming habits and relationship with your daughter and grandson are really beyond your control. By picking up his slack you are giving her a reason never to deal with the situation. She married him and had a child with him, it's up to her to deal with it.