My father passed away two weeks ago in NC. I am living abroad. I flew home for a memorial service arranged by his girlfriend of 30 years. The girlfriend had keys to his apt and car and said that she would liquidate his estate, and that she had a Power of Attorney. She was not cooperative and did not want to share information. She gave me some family photos, my Dad's Bible, and his jewelry box. She paid for memorial service and cremation.

Should I hire an attorney to freeze his assets until the estate can be properly probated?

My Dad did not own much, but owed my $6000 for a car that he bought from me. I have the bill of sale and payment history.

Also, I don't want to find out that I owe medical bills, taxes, or other debts of my father's down the road. The family believes that he was debt-free, but we are not sure.....
Additional Details
Girlfriend presumably paid for cremation and service with my Dad's money, as she admitted to withdrawing money from his account after his death. Also, she has an antique desk that my great-grandfather built and does not want me to have it. I said that I wanted to keep it in the family and she replied that she had it and therefore it "was in the family".