at what age does having sex with children around becomes unhealthy

mom of a 3 year old, and having 4 more kids with not enough room, and with my 3 year old being ultra clingy, he always has to sleep with us. with some research i realized its not uncommon for parents to engage in the same place as long as its not that exposing. the issue is that i read that it has to obviously stop once they're grown up enough. now im not sure what age that indicates. do i wait till he's ready to sleep alone or is it time? he already is aware that we do stuff although not exactly what, so i thought maybe its time, but still. im struggling to pick what to do