Wanted to give you a response. Separation sucks!!! To be brutally honest. And it's hard as every... but just for the first. I've been S from my H for 5 months now. It was so hard at first and I so wanted him back. Well, I started the s without knowing DB so at first I was pursuing, calling, texting my H. And sometimes we had ok conversations but he kept me at bay and it felt awful. It was only after starting DB that I see slight changes in his attitude towards me, and even better I feel much better. I won't lie, I still struggle with the NC and going dark, like right now it has been 4 days since talking to H and its hard for me. But what I also realized lately that when we are feeling detached, lonely, and missing them, our spouses are also feeling the same way. Granted it's a little better for them b/c they have someone else to run to so they have longer tolerance, but they also miss us. And I think that is the lonely feeling that they need to have. They need to feel that sense of loss as well. Granted I am struggle with this myself, but I know even though I don't always do it well, that when I contact/pursue my H, I am satisfy his need to be in contact with me without making any adjustments.
Now as far as it working and us getting back with our spouses, I have no idea. I get my panic attacks as well, and I get to feeling like it will never work. For me, one big fear is that this my H has a son with OW, and I'm will to accept that, I worry that they may have other children and I cannot accept and will not accept, there would be no place for me in that. So it is all very scary. The one thought that helps me is when I ask myself what the alternative is. Do you want to be with your W and things continue how they were? I know my H and I couldn't continue with things the way they were so I know that the S is the only choice I really have since H doesn't seem to want to do what it takes to make the marriage work.
Good luck, stay busy and active, and it will get better.