I don't think this alone would make you a bad wife at all. It sounds like you've had a tough past. Yes you need to take responsibility for your actions, but it sounds like you might be taking ALL the responsibility for your relationship and I don't think you should. He sounds like a very good person, but everyone has faults and no one is perfect.
He might just be trying to get through the pregnancy before making a final decision. But I would say, "I'm very sorry. I am taking steps to change myself and be a happier and healthier person. It will take time, but I'm willing to commit to it and to us. Are you?" I am not a limbo person. So I tend to want to know he's either going to try or not. Otherwise why delay it? It would be nice to be able to plan the future, especially since you'll have two kids.
You do sounds very rational, which is good. You recognize you have a problem and are taking steps to solve it. Don't discredit that. And don't let your husband ignore that either. You are in counseling, which a big step.
On another note, have you taken anti-depressants before? That might be something to consider. Do you think you might have depression which has lead you "wandering through life"? I currently got back on them (after several years off). They help a lot with my depression. I'd talk with your counselor and Dr about it.