Sorry, one quick tiny thought to follow on this: Have you tried telling your IC that she isn't really helping you right now? That what you need from her at this moment is a bit more understanding of where you are and helping you there rather than pushing you in a direction you aren't ready for? Maybe that will help.
The last session she pushed me to tell her what my bottom line is and when I'd like to see him leave. I said "Well I don't want to see him leave ever, but if he has to go I'd prefer he wait until June. The transition will be easier for the kids. As far as what my bottom line for boundaries is here. I have no idea what to tell you. I can say something here and that might not be true if it were to actually happen. Maybe if he gets her pregnant, I guess."
She looked at me in the face and said "Making it to April, his date, or June, your date, is a really long time to be miserable. Do you really think being miserable that long is a good idea? "
I said "April isn't that far. And June is what's best for the kids and my pocketbook. As far as being miserable, I've been far more miserable for far longer. I'm built for misery. This is a blip in time. Besides that I'm not entirely sure I wouldn't be miserable with him gone. It's been like 3 months. I'm not ready to give up on this marriage, and I can't legally make him leave."
"I really think you should give some serious consideration to your happiness and well being here."
And that was basically the end of the session.
Two sessions prior to that she was pushing the boundaries and end date. But left that open ended. Saying it's something I need to consider. Session before last was really pushing on my lack of boundaries, when I explained we have physical boundaries because that's really the only control I have. And he's not allowed in to my inner life if I'm not allowed into his. But it's practically impossible to impose boundaries on a person who is in full on I-do-what-I-want mode.You can say what ever you want but they don't have to respect it. And if I'm not ready to back anything up with legal repercussion there isn't much I can do. I got a reminder that boundaries are to protect ourselves. I felt like lady I know what a boundary is.
Out side of bluntly saying "I need support on the path I've chosen or we can't continue" I'm not sure there is much else I could say.