You will be on a rollercoaster of emotions for a few weeks, this is totally understandable, and I remember those horrible, painful first weeks so well.
I felt utterly broken, and physically in pain. I could barely eat and remember shaking and feeling sick to the stomach. Sometimes I felt like I was in a bad dream, and that none of it was real. All of this is completely normal.
As you know, I really felt that what helped me the most (apart from RL friends and family, and MN) was having no contact at all with Twunt. I had to have limited contact about the kids, but this was always short and brief and detached.
16 months on, I still have the same going on. I avoid Twunt at all costs. It really works. You don't need a contact address, you don't need anything. Your solicitor will send the papers to his work or his parents if necessary. My ex moved, and had papers served at his work. His solicitor will know his address so that will be given to yours. He will need a solicitor (or be foolish not to), because the first letter yours send (if of course you go the divorce route) will be to advise him to appoint a solicitor as you are petitioning him for divorce.
Don't worry about the counselling thing at all. Just pretend it isn't happening. Don't worry that you said you'd try it - it's small fry - he's broken far bigger promises to you. You owe him nothing. If you want to divorce him, then you will be advised to try mediation. As the petitioner, you can do what I did, go to one session on your own, say it isn't working and bounce it all back to your solicitor.
If I didn't have kids, I would never set eyes on Twunt again. As it is, it has helped me a lot going no contact. He hates it, because it means that he has no control over me, he cannot play any emotional games, or blame me, or even try and be nice - because I don't engage with him.
It has also forced him to realise exactly what he threw away. He couldn't say I was the weak woman who nagged him and was so needy. He saw me (and sees me) as a force to be reckoned with, and it's given him the biggest shock of his now very sad life.
Look after yourself. Go with your emotions, it's like the stages of grief, and has to be taken a step at a time. But don't waste time engaging with him at all. Save all your precious energy for yourself, and lean on everyone who cares for you. You sound lovely, and you deserve so much more.