I was very much pressured into it.
Rather like you were pressured into a termination you did not want.
I understand that logically, you now accept this was the optimal outcome.
He now realises this and I am working on forgiving him.
Urging you to terminate is perhaps more forgivable than what he's doing to you now OP. 
He really laid into me and picked apart what I'd been saying. I really stressed to him that it was private but he wouldn't listen. All he cared about is what the counsellor must think about him and what I must say to other people.
How dare he lay into you for having feelings & expressing them truthfully?
Whatever you said, was said in private, to a professional who had guided you to this scheduled point of truthfulness about your own emotions.
What the counsellor thinks of him is none of his business. If he wants to bang on about it, & make your counselling ALL ABOUT HIM, he can pay for his own bloody counselling.
Also - is he a bit dense? Because the reason you are having counselling is so that you can open up to a trusted third party, & not need to burden friends & family with your troubles. Does he not understand how counselling works?
None of it showed any remorse for the way I've been treated, spoken to, or made to feel.
Because it's all about him.
He is refusing to accept that he has violated your trust, interfered in your therapeutic process, & that you have a right to talk to your counsellor about anything you damn well please.
I am really upset with him, but he's not even speaking to me now, he wanted me to say none of it was true.
That is disturbing.
It's almost Orwellian - never mind the truth, chant the mantra & do as you are told. Deny your feelings, & mouth only the words that Big Brother has taught you are acceptable.
But it was all true, I do feel the things I said.
You are still grieving, your feelings are going to be strong, & uncomfortable.
I hope you will speak with your counsellor about how much you have been supressing, that this is NEWS to your partner? Because he's either a dimwit, or has manipulated/trained you into denying your feelings, if they have come as such a shock to him.
He's sleeping in the spare room tonight and can't even look at me.
He's training you into suppressing your feelings again. Just so HE can feel ok.
This is stonewalling. He has taken your grief, your privacy, your therapeutic process, & is using it to manipulate you into toeing his party line - that he's done nothing wrong, that your feelings are unacceptable & must not be expressed, that no matter how bad you are feeling, you must put his emotional comfort above your own.
If I wasn't angry before, I am now.
Suppressed anger often turns into depression.
You are perfectly reasonable to be feeling angry.
It's healthier for you than living a pretence, & walking on eggshells to pretend you are not upset, just to spare your partner's ego & false sense of himself as a virtuous/injured party in this.
You be as angry as you need to be OP. You have done nothing wrong.