Phew !!! That's a toughie...
Are you proposing to go to the meetings with a "Homer Simpson" mind and have your own thoughts whilst the speaker babbles on - for the sake of your family ?
I have to say that sounds good - but others who have experience here may differ on that opinion.
All that pops into my mind is that in Revelation, God calls all his faithful out of Babylon The Great, which proves that some people who know that it isn't the truth will still be wrapped up in it.
It may make it easier for you to ease your family out if you don't have the separation between you.
Just my musings though... it's a crappy situation to be in. I'm sure that loads of posters here will have been in your shoes and they will have better advice than me.