This is one of those times where you go to work in a different field for a while. Perhaps a long while. If you're truly as humbled by his willingness to try as you say you are, and truly as committed to making him feel as safe and secure as you claim to be, then switching a job you love for a job you're okay with is something you ought to be more than willing to do if it gives him peace of mind. And if you do that and start to resent him for it, just remember that you used your chosen field as a vehicle to crush him and that the stain on it is one you put there.
There may be a time down the road when you working in law is something he can be okay with, but for now, you've got a choice. Do you prioritize your career, or do you prioritize helping heal the man you swore to love and honor and then gutted?