Can My Mom Force A Sale Of My Brother’s House Or Win A Lawsuit Against Him?

Location: New Jersey

I’ll try to keep this very brief but am happy to fill in with as much context as needed, just ask.

In 2021 my mom lent my brother about 50% of what his townhome cost so that he could buy it in cash. It was a verbal agreement with no deadline for paying her back, just “someday.” The money was sent from her account to his and the home purchase was made entirely from his bank account.

Fast forward to now, our mom made several very bad financial decisions and is broke except for her social security. She got evicted from her last apartment, and my brother agreed to take her in on a temporary basis. Their initial verbal agreement was 2 months and it has now been four months. He wants her out by March 2027 which will be 1 year since she moved in and is thinking about pursuing eviction if she doesn’t agree to leave.

Our mom has a history of being an absolute snake with lawyers when it comes to finances. My brother is concerned that if he makes any move to force her out of the house, she will come after him legally for the money she lent him. If she does, is there a good chance that she will be able to either force a sale or sue my brother to recoup the money?

EDIT- My brother has corrected me, our mom fronted the full amount of the townhome and he has since paid back more than 50%.

EDIT 2- My mom has personal notes outlining the loan but there is nothing official. AFAIK there is no correspondence regarding it, it was all discussed in person. When my brother paid her back, he added the money to a joint checking account that was made during his late teen years and she withdrew it from there.

EDIT 3- Ok I understand why a lot of assumptions are being made about the situation. I didn’t include personal context because I thought it was irrelevant and would just crowd the post. I’m copying and pasting a comment I just left to explain the situation-

Very long story short, our mother is a manipulative, delusional narcissist. She has no income but came into cash when our father died (they had been separated for 8 years and divorced for 5 and the way she dragged him through the divorce during his cancer treatments and effectively stole his money is a whole other story). She has since squandered all her money on making zero lifestyle changes to save it and had no plan for what to do when it ran out other than to plan on us taking her in. I believe she lent my brother this money selfishly to keep him physically close to her.

He has already paid her back more than 50%. He is the most kindhearted person I know and is ultimately unwilling to let our mother go homeless, which is why he took her in. But it is affecting his mental health and his relationship with his fiancée (their wedding is in less than 2 weeks).

I on the other hand do not have a soft spot for our mother and will never let her live in my house. She will never have 24/7 access to my children or the chance to ruin MY marriage.