check your homeowner insurence

Some homeowner insurance also have ride to cover liability like this. If you auto insurance covers 100k per person, its lawyer will be working very hard for the 500k exposure. I don't think you really need to do anything at the moment beside
have a general idea of how much total insurance you have.

One more thing, 100k per person is really quite high. Very small percents of people carry more than that in their auto insurance. Your LG is clearly blameless. I hope you don't show him this attitude in the current situation.