WR, I also want to share something w/you that I hope I'm wrong about...but because your in-laws are behaving the way they are, you need to be warned. You SIL #1 is acting out and being a nasty bully and SIL #2 is somewhat friendly...the way I see it, they are playing you, i.e., good cop, bad cop, so be careful in what you say to SIL #2. Right now, blood is thicker than water and they are going to gaslight and play you for all it's worth to drive you to do whatever their brother wants or needs. So, my advice, step back from texting either one of them. They are not to be trusted right now. That family is very toxic and will do whatever it takes to bring you to your knees.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.