Stop: take a step back regroup, take a breathe and focus on you. Drop: drop trying to second guess what W is thinking you will never know and you will drive yourself crazy. Roll: try and quit walking on eggshells. We all say and do things wrong. Learn to detach some and that will make it easier right now you seem more worried about saying or doing something wrong that you almost set yourself up for defeat. Roll with the flow abit maybe?
The thing is to learn when the rollercoaster is coming around recognize it and don't get on. You did well at the realtors office you stood your ground and didn't make a fuss about it you simply said what you felt and if I remember right, it pretty much took W off guard and she agreed, but then followed it up with I want it documented for my L. But you did it in a manner that showed respect but that your thoughts do count.
If W wants you to come over a talk that's a good thing, that's when you Db your hinny off and show her your 180's & the changes you are making, take advantage of it, don't fear it. Dress differently than usual, smell good, shave whatever it takes to make a lasting impression. Be the best you can be, don't let W bait you into anything you don't want, she may be in control at this moment, but you have control over yourself and how you choose to be, like I say don't 'react', but 'act' out of your own accord okay?
Do not talk to FIL about this IMO, blood is thicker than water and this can always turn around and bite ya in the hinny! Remember in the end that is his daughter and whether he agrees with her or not more than likely he will back her up.
Keep working on yourself, GAL; PMA; 180's. Stay focused on your goals...