First of all Ginge, please don't be ashamed of the time it's taking, in some cases it can be better to take time, in as much as by the time you do eventually make the move, you will be TOTALLY convinced that it's the right thing to do.
With regard to the therapy, I would send the Counsellor an email telling her that you are no longer going to attend, and why, ie, that he's pulling the wool over her eyes, and what she's doing is basically encouraging his behaviour.
Finally, and I don't know how this might pan out, but what would happen if you left with the boys, and stopped paying the mortgage, and bills on the current home, in order to rent a different house? Would/could he pay when he started receiving reminders from the bank, as of course if the house and mortgage are in joint names, he is equally liable? My only concern is whether this could damage your credit rating, but it might be worth giving some thought to, as it's natural your first thought, when you've been used to paying for everything, would be, 'I can't do that', but why can't you? You might even only have to rent an AirBnB for a few weeks, before he sees sense and moves out, because he can't/doesn't want to pay the bills on the current home, just for him to live in. Of course this idea might be totally crazy, but I just thought it might be worth exploring, and who knows, it might even break the impasse that you're at at the moment. Sending you hugs, and lots of support OP. Keep going, you CAN do this!!