Sorry about your mother and how this may have affected your dd. Understandably you want to protect her. If she can have both parents protecting her, so much better.
You want divorce and want to be fair and just in terms of economics. But economics may not be all that is at issue here. How does he feel about divorce? Does he want it? He also loves dd and, no doubt, does not want to lose her. Can he speak to this issue or is it again silence?
The family matter you describe can be a problem. Sometimes our own are annoying, no less anyone else's. If he prefers to go off fishing or golfing or bowling, etc. he may as well take off. Maybe you don't care for his family either. No expectations on either side could perhaps be a suitable compromise.