Hi @Gemsie1984 I've been thinking about you today since reading your post and how to best communicate my sympathy to you and also my appreciation of your courage and love that you've shown already.
From what you've said, you must be a very strong and impressive person to be where you're at now, and I'm delighted that you have a supportive partner, healthy pregnancy, and means to ask for help when you're feeling like this.
Personally, I think your dad and his partner undeniably come too far down on the list of priorities to behave this way and think you'll bend to their side. You have wonderful children, and a precious bean to care for, not to mention your own mental health. This all comes way out in front of their views and I'm sure you'll be supported by the vast majority of people in this way.
I know how hard it is to put space between you and a parent, having had to do this myself for my first trimester following repeated drama. It is hard but it can turn out well in the end.
In the meantime, you are deserving of love and support, and they are big enough and ugly enough to have a think through their own issues!
Sorry if that came out all muddled. Wishing you all the very best and sending big (heatwave-y!) hugs xxx