Mothers Denial

My mum acts as if nothing us going on. As far as I know, she's not said anything to Martin either.
She caught us having sex six months ago, with Martin fucking me from behind on the sofa, and never said a word. And since being in lockdown, Martin and I haven't stopped having sex.
In fact only last week as he was eating my pussy, my mother called through my bedroom door, that our evening meal was ready.
She knew he was in my room and believe me, when Martin's sticking his tongue up my pussy and sucking on my clit, I'm not quiet when I orgasm.
Eating our meal, she smiled at Martin and asked him if they're booked holiday money had been refunded.
My step father replied "No not yet, and I think Jess and I might go to the cottage next weekend".
My mother smiled again and just replied "Ok honey".
It's not as though they're not having sex, as I can hear them fucking every single night.
As I type this, Martin is driving me to the cottage he and mum bought just before lockdown. Well be staying all weekend and all weekend I'll be having sex with my step dad.
Mum kissed me goodbye this morning and said 'Have fun'.