Need Some Advice: Trustee For (aggressive) Mentally Ill Brother

Location: New York City

All,

My elderly parents have a decently large sum of money and are in their 80's. They are working on updating their will, and there have been a lot of conversation around who will be the trustee.

We are two brothers - my parents wish is to split their estate in two, I would get 50% outright they believe/I am responsible with money. My brother is 2 years older than me, unemployed and has pretty bad bipolar disease to the point where we haven't talked in 2+ years, with multiple awful experiences with verbal threatening abuse and some previous physical altercations including myself and my husband. He blows through cash like crazy, and is currently 150-200k in debt, as I understand it.

For this reason, my parents are creating a trust for my brother where he'd get a certain amount of money each month (many thousands a month). There would be a clause stating that if he tried to sue me or the estate, he would be disinherited.. My parents are naturally worried about his wellbeing but also feel a trust company would not be as benevolent to my brother and would also cost around 1% yearly. They've asked me to be trustee so I believe my role would be : managing the financial growth of his portion, ensuring the set amount of money adjusted for inflation was properly doled out (seems fairly automatic), but also paying for any insurance/medical bills that arise .. so I'd have to engage with him to some degree. I DON'T want discretionary power as I know my older brother would threaten and make my life hell.

I would really welcome any advice on this - if the controls are tight around the monthly stipend and I'm not given a lot of leeway, could this still work? I would never want to be in a position to have to say 'NO' to a new house downpayment, etc., but I can imagine it spiraling out of control and being an awful situation for me and my family. On the other hand, my parents trust me and want to die in peace knowing my brother and his 50% estate would be taken care of... some amount of money would also be dispersed to his children (who he does not have any connection to after the divorce with his wife over similar behavior).. that part does appeal to me as I would want to be sure they are in a good place to receive those inheritances.

anyways, sorry to ramble - appreciate any and all advice and thank you. Please ask any questions and I'll follow up