Can anyone else recommend some specific names of counselors (both marital and personal) or ways to get that information?
To Stephanie.happy, I think you can consider trying counseling first; not necessarily because it would make your marriage work out, but to help you come to a decision. If your husband won't go with you, you can try to go by yourself. The counselor won't make a decision for you, but they might be able to help you really consider all your options, and figure out what the underlying issues are so that YOU can make the best decision, which is what it sounds like you are worried about.
Since my parents stayed together (not a perfect marriage, but they were able to tough it out), I cannot give personal advice, but from what I read here from other people there is no easy choice, and I really wish you the best of luck. You sound like a caring mom who is trying to do the best thing for her child, and so no matter what you end up deciding to do I am it will be the right decision for your family.