The question

My boyfriend and I never married. We were together for over 20 years. We had a mortgage on our home together but I am not on the deed. His brother is on the deed but not on the mortgage. We all lived together. My boyfriend passed away a couple of years ago and his brother and I thought everything was fine until my boyfriend’s estranged children, (who have never paid a dine toward the home), started saying that the house is legally their inheritance. My boyfriend did not have a will but his intent was for me and his brother to continue to live in the home. I assume because I am not on the deed, just on the mortgage, I have zero ownership. His brother however is on the deed. Does he now have complete ownership of the home and can he will the home to me or add me to the deed to transfer ownership to me once he passes away? We just found out that he has cancer.