Very unlikely that homeowner's insurance will cover this. Negotiate the medical bill.

How should I defend?

Tell your insurance company to defend you. They should take care of this!

It is low, but- when was the accident? It does not sound like your treatment is complete. Get a lawyer.

Can an insurance company sue me for an accident that wasn't my fault, just because I didn't have insurance at the time?

It sounds like the insurance company representing the woman has now decided that because you did not have insurance, they can come and pick on your...