I have a question about survivorship.

My mother has been with her partner since the 90s. When they met he was still married. His wife had an affair in the 80s and moved out of state to one of their condos.

My mother at first, demanded they divorce. Her partner told his wife he was getting a divorce and she begged him not to. She was getting him to pay her health insurance and car insurance. My mother being the kind person she is, felt bad and told him not to divorce her.

Now years later, he has stage 4 lung cancer. He wants to make a will and leave his share of the house to my mom. His wife said no. He has no choice. That the house was a survivorship deed and no one can sell unless he or the wife dies.

Even if he divorces her... She says that it won't change the survivorship.

I am contacting a lawyer tomorrow. But my mom is so upset thinking she has to leave the home she's lived in over 20 years and the cheating wife gets the house worth over 400,000

Is there anything they can do? Is there no way out of this survivorship?

They live in Maryland if that matters.

Thank you!