I am sorry you are going through all of this. This is a lot to deal with, and being six months pregnant has to be adding significant stress to this situation. I am sure that day to day you sometimes feel that you are about to go crazy with all this stress.
Let's look at this one issue at a time:
Your feelings about your current relationship do not seem at all inappropriate. More or less constant fighting and conflict will make most people very sad. To top it off the man in your relationship now is not open to counseling and is employing what I call the hope method of relationship recovery; You tough it out and hope for the best...which mostly does not work.
Why so much fighting? Truth: This relationship is relatively new psychologically speaking, yet is it going through very complex stresses such as waiting for a divorce, a pregnancy, a potential marriage and the raising of very young children.
For any couple this is more than a plateful, and to add all the complexity of this to your life such as your ex husband and his needs; it is a lot. It is no wonder you feel as you do. Fights are common when this level of stress is present. But that does not mean that he should just "plough along" either. You both need support. For him to say that he thinks you can do this yourself (him and you) is a bit shortsighted. I will say it is very male behavior, but that stubbornness does not make it right.
Without a doubt you need support. Even if your current partner will not go to counseling for whatever he reasons, you should go. You need the perspective, support and the unbiased help this can provide. You are worth it.
The hyphenated name: You are not married to the father. This is a child who needs an identity. It is possible based on the conflict that is seen in the relationship that you both might not stay together. The hyphenated name is XXXXX XXXXX idea. I am not sure what his issue might be on this, but it certainly makes sense. It is a good call. I see nothing wrong with the choice.
This is not the time to decide anything so huge as going back to your ex. That is a decision for another time. But now the key is for you to be at peace. You need it. It is too much to be exposed to constant fighting and conflict. I would suggest that you choose a path where there is the least conflict. If that is living with the current man and you disengaging and refusing to fight and talk unless it is civil, so be it. If it means living with a relative or anyone else, so be it. (or even your ex if things get that bad) But The key is less stress and what you are facing is not good for you or the baby.
Pursue peace even if it means giving up a lot. You do not need emotional fights and drama on top of everything else. Choose the path that offers this and once the baby arrives, with a counselor's help, work out the next steps. Steven