Welcome back, and sorry you're still in this situation. I couldn't sleep tonight and so I just re-read your story.
Honest opinion? Your most recent update sounds like nothing much has changed at all. In your very first post here in July 2019 and countless times since right up until the present, your W was threatening D and you were telling her "ok, go ahead" and she wasn't taking action on separation/D.
3.5 years is a really long time to be living this way. I imagine it's a drain on you emotionally, mentally, and possibly physically.
How old are your kids? Earlier in your sitch you mention them sleeping on a mattress next to the martial bed, so that makes them seem young, but now are talking about discussions you and your W have with them about your marriage and the family and possibly getting through school before divorce, so that makes them seem older. It sounds like your W wants to get them through high school and then divorce so the status quo is actually to her advantage. The question is...does that work for you? Or, are you tired of it and ready to take action on your own and move on?
One thing that occurred to me is your threads seem very focused on your W's actions and state of mind and has very little mention on your GAL and self-development. Are you in the gym? Have you taken on new hobbies, activities? Met new friends? I joined an adult sports league, started grad school, joined a club, going to parties with friends...etc., and that has helped me a lot. Hope you're finding something to make the best of your life.
Hang in there...
Me:39 Ex-W:37 M:7 T: 9 S:6 D:3 BD/IHS/Confirm EA/PA: Feb '20 OM1 affair ends: May '20 W/OM2 & moves out: June-July '20 W files for D: Jul20 OM2 confirmed: 9/2020 Divorced: May '21