You have to trust that she's having doubts. The problem is when you feel bad, or when anyone feels bad, all their senses focus on all the negative stuff and everything spirals downward.
Focus on the positives. She IS nice to you, she hasn't left your home, she hasn't moved out, she is meeting with a mediator.
You hae to trust yoruself and that what you are doing is good for YOU and her. This isn't all just for her, you will feel better inside having done all these changes to clean up your life.
Its a tragedy that this had to be motivated in this manner, but you are doing good things for yourself. You are living a life you can be proud of. Can SHe say the same? Can HE say the same? You are coming out on top here.
I would talk with a lawyer yes and find out what your legal position is rather than relying on second hand rumours.
The idea is for you to do something very unlike yourself so she can see you are NOT the guy she left. You want her to see that you are a NEW guy, much better than the one she walked out on, and even much better than the one she's looking at now.
There's hurt and resistance there still...so you have to do some daring stuff to catch her attention. Its kinda like in school when there's someone you like and they don't realise you exist...it takes some daring...and in this case she doens't want anything romantically declarative.
Yes, it owuld help if she was clear on what she was looking for in her life right now. It would be GREAT if she would agree to see a marriage counsellor/therapist.
The idea there would be to sell it as "we just want to find out how all of this will affect our son and make sure everyone is coming out of this with the minimal amount of upset possible"
I think that sounds safe enough. Only her parents should be hte one to pitch that idea, not you.
See if you can get her to attent a marriage therapy session. She doenst have to go WIHT YOU, she can go alone or you two can attend separate sessions.