I hope you're ok OP - it sounds like you are having a really difficult time and need support.
The difficulty with a choice like whether to have another baby or not is that it is a binary - you either do or don't, there's no way to compromise. It puts you in a terribly difficult position if you and your husband don't agree. One of you has to not get what they want.
This is going to sound harsh but please know I'm hugely sympathetic - but you can't force your husband to have another child. He has had much right to decide if he wants to have another child as you. His decision is valid.
Your feelings are also valid - you're allowed to want another baby. That leaves you with a difficult decision to make; what is more important to you? Is it your husband, or another child? If the answer is your husband, that means accepting his decision and moving on. If it's another baby, you have to decide if you're willing to leave and go it alone.
What you can't do it be miserable indefinitely. It isn't fair on you, your children or your husband for you to be so upset all the time. You need to find a healthy way to move on.
I wonder if there are deeper issues at play here? It sounds like you have deep-rooted insecurities about your abilities as a parent. Your conclusion that your husband must think you are a bad mother isn't rational, and I wonder if you have self-esteem issues which are manifesting in this way? I think it's really good that you're trying to speak to your counsellor and I hope that you get an appointment before too long. It might also help you to research CBT, as there are excellent resources online which could assist you.
I don't think it's unreasonable that you want more support from your husband when you are upset. I also think however that he probably feels very attacked, and that you are trying to make him change his mind. I think you could rebuild a lot of trust in your relationship by telling him that you understand and respect his decision and won't try to change his mind, but that you are still sad and hurt and need help to move on.
I wish you the best of luck OP and I hope you can soon find a way out of this painful time.