This is something which I think will be helpful to consider.
You say, 'no'. He says, 'why?' Do you know what - you do not gave to give a reason - none at all. You do not have to give a reason, an excuse or anything. Just because someone asks a question does not mean that you have to answer it - it's part of sales training, how to get into a discussion because once you have an answer to an open ended question you have the foot in the door.
I can't think of any conversation following the 'why' that doesn't leave you vulnerable to manipulation. I'd just change the topic conversation to the weather. Or ignore it completely. But then, I was born with a double helping of awkward. I know it isn't as easy for you. However just knowing it is an option may help.
I think this is important - you do not need to justify yourself to him or anyone else. Sorry, but I hope that helps. When you've been backed into a corner for years, it's really hard to hear that. It is up to you how and when you act on any of this, but honestly, you have value, you have intelligence and you have the right to make choices. And one choice is to walk away from their script.
Of course he is acting like this morning didn't happen. He is Mr Reasonable, Mr Calm, Mr Sane. Any emotional reaction will bounce off that leaving you upset and confused and looking like you have mental health issues and he is justified. If this doesn't work he may go back to shouting etc. btw - of course he is busy with his Bibles, he needs to look like Mr Respectable Churchgoer to the pastor and try and paint you like a crazy woman. Expect him to do all he can to undermine and upset you just before the pastor arrives so that you cannot be composed and lucid. He may pick at something like housework or the meal - just to put you on the back foot. I am really not sure that this meeting is a good idea, I hope you will be okay. You are bound to feel a bit under siege.
When I have felt backed into a corner and hounded by questions that I don't want to answer, I sometimes focus on something else really hard. Do you know any psalms off by heart - working through them may help if you are in the middle of the storm. And do not commit to anything until you have had time to pray about it. You need to make decisions away from immediate pressure.
Still praying for you. Also, you sound really beautiful from your posts. I wish I had a scrap of your dignity. Sorry about another long post.