Welcome IRIA... sorry you're hear. Sandi and Bustorama are a great source of guidance and thoughts, listen to them.
My W and I are at the same point. She wants to be great friends and better co-parents, but not married. We even have children close to the same ages. I will tell you right now that what's coming is probably the hardest thing you've ever done. I've put it right up there with dealing my father's death when I was 18. Nothing else compares.
You will need to learn to fight every natural instinct you have. What you have to do will seem counterintuitive and wrong, but it's not.
And there are no guarantees. When I first started here, (ha... just realized you and I got the bomb only five days apart too!) my W and I were not talking, not being civil, and it was terrible. But I've listened and worked... not perfectly, I've made some screw-ups some pretty big some pretty small. But things are "better".
However, "better" doesn't mean we're working on our R, our moving towards recon, or anything like that. My W still wants to be apart. However, our house is at least civil now, and I would say that on most days it's even warm. We laugh and joke, we play with the kids, we even ML every so often.
Two months ago I cried every day and almost all day. I couldn't function at work and I was miserable. I think yesterday I only teared up and cried a little for maybe two or three minutes. I actually had a whole week last week where I was largely functional at work.
One big piece of advice you will hear is that you need to "detach". It's an amorphous concept that's hard to nail down, but critical to understand. In essence you need to not have your W be the center of your universe and not have your emotional moods and well-being be tied to hers. Understand that, while you have your issues and your depression, she has problems too. WAS have problems. Your W is looking at a future as a single mom of three kids who is 43 years old. If that doesn't scare her deep down then she's insane. She probably won't admit her fear to you or her misgivings, but they are there. They will take her up and down this emotional rollercoaster, and if you don't detach you will ride it with her.
The other big piece of advice I would give you, that has really helped me, is to understand where she is at right now. She is not considering leaving you; she has already left. Physically she may still be there, but in her head she is already single and alone. You are already "just friends" or "just roommates". Your work now is to improve yourself. Not so that she doesn't decided to end your M... that ship has sailed I'm afraid. But so that, in those dark moments of ambivalence and worry when she looks at her decision, she is given reason to question whether it was the right one. I spent a lot of energy and time doing things that I thought would stop my W from deciding to leave our M. This also meant I reacted to every note, text, comment, and convo. It drives you mad.
Once I realized she's already walked away it became easier. Less pressure. Time + consistent change = something your W can believe in. You'll hear that a lot. So come to grips with her already being gone and that you are changing for you, and that those changes over time may give her pause about her decisions.
Last thing... also realize you have the power here. Your W may get to decide about separation or divorce. You cannot stop that process. BUT, she doesn't get to decide when you stop wanting to work on your M. You only move on when you want to move on. That may be three months, three years, or 30 years - your call. You don't get to control her decisions, but by default she also doesn't get to control yours.
So... no pursuing, no R talk, no ILY, no affections, and honest, hard work on yourself.
Eh... it's going to be winter, what else did you have to do anyway?
Married 6 together 8 Me:38 W:31 second marriage for both SS12, SD10, S6 Bomb: 9/8/11 (day before our 5 yr ann) W moved out: 2/18/12 D final: 11/12/12 Share S 50/50. Spend as much time as I can with SS & SD