Sister, please take this in love. Good parenting is hard and the following will be hard (bc it will involve CHANGE for you) but it seems you're having it hard anyway.
So:
I don't know his age, but an elementary school child should not be on the internet without your permission - period. Otherwise, who is parenting whom? Tell him "Off, now".
I prayed for you both.
Even High School age, the rules change some , but you're the adult. You make/ they follow YOUR rules.Your house. Your rules. **He simply knows you will cave based on history. CHANGE now. It will be a fight for a while bc he's used to his way. But CHANGE now or you're in for an even wilder teen years! I was a single mom of twin boys from infancy. Together we prayed, read the Bible, always went to church together and followed Jesus' lessons and guidance. **Jesus had boundaries and gave CINSEQUENCES** (eg He was legitimately angry when His Temple became a market). They are good grown men with children of their own now. You are the adult. Respectfully, I ask you to please take the difficult adult role.