My fiancé hasn't told his parents..

That I'm pregnant! We are 35 and he lives at home but so do I. We are engaged but I am 3 months along. He hasn't told his parents because they are religious and he said they were angry in 2001 when he told them about getting this bitch he was with pregnant but he was 20 and his family worships that whore. Anyway I haven't posted on FB about my baby! Should I leave him if he doesn't tell them this weekend?