If he’s concerned that he is HIV positive ( since his teens ??? ) , why has he been having unprotected sex with you ?
Since he is so concerned about STI, why did he have unprotected sex when he had an affair? And why did he have unprotected sex with you afterwards and then insist that you wrote tested for STIs .
So he has this secret health anxiety that he’s has since his teens but he’s managed to keep secret from you and doesn't affect any other aspect of his health ?
That doesn’t make sense.
Slightly worrying about lumps isn’t healthy anxiety . People with health anxiety tend to Google everything , find the worst possible outcome and then obsess about it, go to the GP or hospital seeking a diagnosis. Often they won’t be reassured and are convinced the doctor has missed some serious illness.
There are lots of threads on MN by people who struggle with this issue. It’s not something that they can keep secret from their closest friends and family, even if they want to .
They take steps ( logical or illogical ) to avoid doing anything that they see as risky. Look at what some people did during the pandemic - never going out, bleaching food packets , insisting that family members strip off all their clothes in the garage and shower and then boil wash all their clothes.
Your husband has two family members who have cancer. Which is such a common disease that everyone in the UK who has a large family will have two relatives with cancer.
But he doesn't worry about getting cancer. He supposedly worries about getting HIV so he has unprotected sex with you AND another woman at the same time???
And he’s ever even mentioned this to you? Or sought help from his GP, psychiatrist , psychologist or anyone else ?
And why HIV? There’s other things he’s much more likely to catch from unprotected sex than HIV.