Not quite sure how to handle this or even which of us is in the wrong.
I have a DS aged 15. He lives with me 5 days a week, and at his Dad's the other two nights. His dad and I have been separated since DS was 7 but we get on reasonably. For the last three years I have been seeing a man every few weeks for sex. This arrangement works well for me. The man and I have never been on a date or even met anywhere except my house other than the very first time we met. He has never met DS, and only comes round on the days when DS is with his dad.
A few months ago DS had forgotten his sports kit so texted me saying he was coming to get it. I was with my male friend at the time but went downstairs and gave DS his kit. DS wanted to come inside but I said I had a friend visiting and it wasn't convenient. Obviously I wouldn't have wanted to deny him access to his own house but in that moment I didn't really have a better idea and he seemed fine with it.
The next day when DS came back he asked me outright if it was a male friend and if we had been having sex. I told him it wasn't an appropriate question to ask, but he said that he didn't like the idea of a strange man being in the house. I said that I was an adult entitled to a private life.
Since then, most times he has come back from his dad's, he has asked the same questions. He has also told his dad that I am seeing someone and makes snarky remarks about me being busy having sex etc.
I admit that it wasn't ideal on the day of the sports kit incident. But I am always 100% discreet with this man, and surely deserve a private life. I don't want to talk about whether I am seeing someone or not, because the nature of the relationship isn't one I want to get into with DS, nor do either the man nor I want the man to meet DS ever.
What would you say to DS in these circumstances? I could just lie and say that there is no man, but that would be a lie. Should I just be firm and tell him to stop asking? Or tell half the truth?