This may be to be the worst you have to endure. Many of us hit our rock bottom 3-6 months out from d-day. It's excruciating, but life does get better.
Whether this is the worst or not, Feeling your feelings lets them go. The grief you feel is normal - you are processing the feelings that come with a big loss, so ... lots of feelings - and it takes time to process lots of feelings. Manyof us get stuck in anger. Getting to grief this early is beneficial. (IF you're not aware of anger ... don't worry - it will come.)
One of my fears early on was that we'd do the work, and my W would decide she didn't really want to be with me. That's a real fear, and it's a real possibility. IOW, like you, I feared that my W might really want to dump me. A couple of thoughts helped me a lot.
But that wouldn't necessarily be a bad thing. If one really does the work, one comes out stronger, knowing what one wants and probably being more effective in getting what one wants. So I consoled myself with thoughts like: if W wants D, I'm better off with D, too, even though I want R.
First, I realized that I might decide I didn't want to be with my W after we had done the work. I had power, too.
Second, and more comforting, I remembered that we got together for both healthy and unhealthy reasons. The work we had to do to R reduced the number and power of unhealthy bonds, and that made the healthy ones relatively stronger. We had chosen each other once. It was very likely we'd choose each other again.
fBH (me) - on d-day: 66, Married 43, together 45, same sex ap
DDay - 12/22/2010
Recover'd and R'ed
You don't have to like your boundaries. You just have to set and enforce them.