Hey there, iamsoblind,
You have been attacking all of this so fast and hard, I'm sure you haven't had much of a chance to really absorb it all.
Even though you know you are pursuing the right course of action for yourself, you will certainly have moments of regret and sadness, confusion and disillusionment, loneliness, all that. It's totally normal. No matter if he devastated you, there is still a history you have together and it's hard to wrap your mind around all of it, given your new reality.
Be gently with yourself. It's okay to be down or sad. You need to grieve what you lost. It's part of the process. Don't beat yourself up for it.
You are doing great. This is an excruciatingly difficult trauma to get through. Be kind to yourself.
How are your DS and DD doing?