sexy time with new boyfriend

Been seeing someone for about 5 months and have spent the occasional night with him when my kids have been at stb exh, but this contact is unreliable and irregular. As such new bloke regularly comes round to my house otherwise would not be able to see him. I fully trust him but it is too early in the relationship for me to want to introduce him to my kids so he comes round once they are asleep.
My children are reasonable sleepers and sometimes wake at night but not very often and even less often would get out of bed and wander around.
Anyway, things have got a bit heated when bloke has been round last couple of times and i was wondering if anyone has been in this situation and whether you have a point you would not go beyond sexually when kids at home.
When ex H lived here (their dad) we had a active sex life but mostly in the bedroom. I would not take new bloke upstairs if kids there so all in the sitting room if that makes a difference?