DSS (14 yrs) has his own keys to our flat, as he comes round one night a week straight from school before we get home from work. He's generally a good kid & we felt he could be trusted. The only rule was that he never came over without letting us know first.
Everything was fine until saturday, when DP got home from work to find windows closed that we'd left open and a different game in the x-box from what he'd last played. When I went on the computer porn sites were on the drop-down menu of recently viewed websites.
When DP phoned him he said he'd just popped in to give back a DVD he borrowed, when asked why he hadn't told us he said "My mate was meant to text you" so we now suspect he was round here with friend(s).
I am furious. I have worked so hard over the last 6 years to build a relationship with him, and I thought I had done alright. TBH I feel betrayed, the thought that a total stranger might have been in my home really freaks me out. DSS is due to visit next in a couple of days and I don't know what to say / how to treat him.
What would you do?