I am very sorry for your situation. I just wanted to give you my two thoughts on this:
I am pro-choice, so if a woman truly feels like carrying an unexpected child to term is not an option for her, I think that terminating the pregnancy should be an option. BUT, if you are considering this, you have to make sure you are honest with yourself. There is a Planned Parenhood in Fond Du Lac, you may want to consider giving them a call and see if they can refer you to somewhere closer, if you are truly considering this.
There is obviously something else that this pregnancy going on here, your husband even admitted to this. Terminating this pregnancy would not fix your marriage, take that into consideration.
It is very positive that he wants to get counseling by himself, I encourage you to do the same. He may need to go by himself for a while before he is ready to get marriage counseling.
The other thing I have to emphasize for you: do not even for one minute believe that this is somehow your fault, no matter what he tells you about feeling betrayed and whatnot. He is an adult, a grown man who knows how it works. If he was so adamant about not having any more children, he could have taken steps to protect himself. I assume here that he knew that you were not on contraceptives, AND EVEN IF YOU HAD BEEN he has the same responsibility as you did to prevent an unwanted pregnancy. It takes two to tango and both, man and woman, need to take measures to protect themselves if they are so adamant that they don't want kids. Birth control fails, people make mistakes - this is a shared responsibility, not a situation in which one party takes all of the blame.
Good luck.