break the news to MIL...update 5.,7,8,11 now baby rabies?? pg 12.

I have been lurking a while, but this is my first post. My MIL has over time (since the twins were born) slowly become my BEC. She says PA things all the time and thinks I should always take her advice (while I roll my eyes and so don't) it was much easier when we lived 11 hours away and only saw her 3 times per year....now we live about an hour away and see her every few months.
I can give you examples of previous issues if needed.

My current dilemma....I'm ecstatic to be pregnant after our FET. My betas have been high, so there is a possibility it will be another set of twins. MIL is not supportive of us having more children for some reason and made that very clear when DH told her 2 years ago that we were looking to do IVF again. She also recently made comments about "too many kids" with a CBF when I told her our good friend from HS was expecting their 3rd child.

We never told her about the baby we lost last summer. My family has been supportive and excited throughout this process and we told my mom today. We will have to tell her at some point. We keep her at LC, but the cat will be out of the bag as I start to show. How do we tell her 1- I'm pregnant and 2- her opinion on the subject is NOT wanted......