Sorry for your situation. This is called subrogation in insurance terms. Do a google search on renters fire insurance suing and subrogation. A very common situation for renters apparently.

I would NOT talk to the insurance company again until you talk to your own lawyer. Problem here is a lawyer is going to want a retainer fee up front just to get things rolling. You should be able to get a free consult, but after that they're going to want some money up front. Maybe with the free consult, they can tell you your chances of winning a lawsuit if at all.