Seeking expert testimony is a sign of strength. A personal relationship with a caring professional is proven clinically effective.
I believe that I can help with this situation.
You relationship with your husband reached its lowest point when he left you.
Now it is moving back to a better place. Your issues have not been resolved but now, at least, they are moving in a positive direction.
He is a volatile and stubborn person, and it seems that his son is just like him.
What he has proposed doesn't seem that unfair. He will be staying with all of the time except for two weekends per month.
He loves his son and wants to spend some time with him as well. That is not unfair. He will be around most of the time, including every day after work.
If you can permit this compromise, then you will be in a better position to work on your relationship and find a way of stopping the feuding between the two brothers.
This should not affect your son. His daddy will be there almost all of the time. He cannot expect his dad to ignore his other son. That would not be fair. It is certainly preferable to him not being there at all.
Your husband is not cheating on you, not running around, and is trying his best to satisfy everyone by making compromises. He has a sense of fairness that is to his credit and will benefit you as well.
I suggest that you accept this arrangement and at the same time find a marriage and family therapist to work with you on solving this problem. It may be hard for you to see at first, but you can work through the problems, the biggest of which is how he treats your son when his son is around.
Of course this is a glaring problem and has to be dealt with, but it will be easier if you are getting along and living together most of the time.
In the meanwhile you might consider getting the help of a family therapist or counsellor to help your family resolve these issues. In the long run this would be you best and long-lasting solution. This marriage is worth saving and fixing the problems that you now have.
Here is a place to look: http://www.psychfinder.co.uk/ Here is another: http://members.psychotherapy.org.uk/find-a-therapist/ Here is a third place: http://www.itsgoodtotalk.org.uk/therapists/
And a fourth place:
You could "shop" together for someone that she might want to choose to help her. She needs help and this is the best starting point.
Think positive. Things are already moving in the right direction. You need give and take to resolve this successfully.
I shall keep you in my prayers for the patience and wisdom to see it through.
Elliott MAE, LPCC, NCC, CCMHC