I feel like it will be a volatile return to my home so I am going to be very careful not to stir the pot. She is very likely going to have a moment when she tries to yell at me and blame me for all of her problems. That's going to be difficult, but I think I'm ready for it.
You may never really never know what caused it. The best advice I can give you is to take stock of how you feel about yourself as a man and work to improve on those things. For me it meant my physical appearance, new clothes, etc. It also meant getting off the couch and dong more things with my D's and being active outside around the house.
Try really hard to not get sucked in emotionally, IMO early on it is very important because she is just looking for reasons to confirm she made the right decision. Anything she can grab onto to fuel her fire she will, right now you can't help your R you can only hurt it. If you feel yourself starting to get sucked in please catch yourself and let your W know you would like to have this conversation at a later date in a calm manner. Listen, validate but walk away in a calm manner if she starts to yell. Not getting sucked in is how you can get respect back. If you yell back, or go tit for tat the cycle will continue.
