Honestly I'd look for something else. YOUR family should come first and the fact that your inlaws keep asking you to take a pay cut when they know you're pregnant and trying to prepare for having a baby is wrong. I'd give them your two weeks and train someone else during that time.
Look for something else while you still can. Its hard to take a pay cut especially @ the same time as your husband. Soon they'll be writing out IOU's. Family is important but so is your financial stability. Start training someone, that way your conscience is clear. Good luck!
I hate to agree with the above posters, because I feel like your in-laws will just blame you if the business fails. And maybe the business, if shaky, will fail faster if you leave; but if it is already so shaky that everyone has to take one pay cut after another, it is probably going to fail anyway. So like the others recommend, I'd say look for another job. In the meantime, document EVERYTHING about how to do what you do, and when you give notice, hand over the book and tell them that this covers everything someone would need to know to do your job. Only problem is, they will still blame you, if the business does close. I'm so sorry.
ps -- if you are wanting not to sandbag a future employer by being pregnant and then leaving to have your baby, you could temp. It's pretty handy for a pregnant woman.
I agree with the women who posted before me. I would look for another job, but be sure to write everything down on how to do it so that way they can't say that you left them "to do it all". Just like AnnieBrooke mentioned, temp services are good when your pregnant because they can always dismiss you when you give birth. A lot of my friends went through a temp service when they were pregnant. Also, if you were to quit, I'd ask them if they were making any pay cuts to their checks to save money. I hope it all works out for you.
thank you everyone for your comments. today i already started looking and even sent some resumes. i just needed that little push towards what i felt i needed to do. i hope one day my inlaws will understand and not blame me.