Your instincts seem correct on all counts. I see a lot of depression, but a willingness to go through with it. And you are correct that becoming adversarial about it won't end well. And will protract all of it.
I suggest you go with her wishes while she is in this frame of mind. She may not stay so friendly about it, so get it signed quickly. I don't think I'd even talk about it with her knowing what I know now. Keep your comments as brief as possible. I let mine know it wasn't what I wanted, but was going to go through with it. That may not matter or be appropriate for you.
Try not to make any future promises in your sep agreement either. You can't see the future, so you don't know what things will be like, and you don't need the added burden of a contract telling you. If she's as nutty as the squirrel poop she makes out to be, things won't stay this friendly. You may only have your contract to fall back on. Plan accordingly remembering this is her choice, not yours.
As for feeling like you are taking advantage of her or leaving her "broken"... believe me, that is what you MUST do. This isn't about you. She needs to see it through on all counts and she'll need the good with the bad. These were her choices and you helping her won't help her learn new skills.
I felt the same way with mine. I helped for a while. But she had other resources she could fall back on, and did. Things I didn't see at the time.
Your W will be fine. She will need to feel the pressure and the feelings. She won't grow until she does. You don't need to be mean about any of it. Let her do that. But you can protect yourself and the kids with the idea that this will become adversarial later.
Oh. And don't let the lawyers get in your heads. They will try to twist you into anger because they know it protracts the divorce and brings them revenue. Shop for a lawyer wisely my friend.
More later....
AJ
"Our lives begin to end the day we become silent about things that matter" MLK Put the glass down... "Yesterday I was clever so I wanted to change the world Today I am wise, so I am changing myself."