Joblot - you have done really well - your first post was about three weeks ago, and since then you have finished the relationship, which you know was the right thing to do. But three weeks is a short time for your heart to catch up with your brain.
I get the impression that you want to rush through all the emotions involved and get to the other side. This does take time - actually it takes as long as it takes. The trick is to accept this, and not question every emotion. What you're going through is like a bereavement - and therefore you have stages of grief to work through. You will feel anger, guilt, sorrow, regrets, etc. This is natural, a process to work through. Actually, that's wrong, you don't have to work through them at all - you have to accept them, and go with them. You feel exhausted physically and mentally - of course you do, that's part of it too. But rather than think "have I done the right thing - I feel so bad because I feel like this", think, "ok, today I feel guilty, but this too will pass".
Don't spend too much time analysing your feelings and guilt tripping yourself. Because then you won't be able to see the wood for the trees. The fact is that you were in a lousy hurtful abusive relationship, and you've got out of it. There are still loose ends to tie up. But make these as simple as possible.
I have to have minimum contact with my ex, because we have 4 kids. But that is as far as it goes. He would like more, but tough, for my own wellbeing, I keep to contact-about-the-kids only. And then it's brief, civil. I don't do small talk with him, I don't chat about anything. I will never "chat" with him again. This isn't me being cruel, it's me realising that I simply can't do it, because it will set me back.
Stop worrying about how far you have to go, and focus on how far you've come. And be gentle on yourself. You sound a lovely and warm, caring person, who has had an absolutely lousy time. It's over - the future will be great for you, just ride through the next few weeks/months and accept your emotions.
Now - can you install me an en-suite bathroom by tomorrow? 