Good morning, I would like to help you today.
The entertainment business can be a very messy business, I do know from experience as well. It almost sounds as though "Jane" didn't have a will; otherwise, how was her "best friend" able to take control of her money and her health? No one else had/has any input into "Janes" estate (if so, they should be contacted). I do not think that you are a "whimp"; It only seems that you were trying to help as much as you could (trying to take care of "Jane"), but stay out of the situation at the same time (legal). I do think that it would be a good idea to contact "Jane's" ex and his children, because as you mentioned, that's who she agreed to leave everything to, and I am sure that it is what she would want you to do. If you can contact them discretely and let them know the scenario, this would be best.