Asdf, your will at this time leaves 50/50. but I have serious concerns re the past manipulation you've been subjected to and appear only now to be recognising. Your original post - you ignored things for the easy life, you went along with things rather than ruffle feathers. You allowed your husband to treat your brother, who you say has mental issues, appallingly within your home and his own home, and said nothing. You tried to talk to your daughter about issues and she burst into tears.
What happens if (when) your daughter feels you are unable to control your finances and suggests she take over? You were willing for her to take on the duties on settling your late husbands affairs and honestly that should have been your job - she cut your son out of the decision making. What happens if you (God forbid) fall ill and your daughter suggests she take on Power of Attorney? Can you say hand on heart your daughter has your best interests at heart, the daughter that treated you so badly as a teenager, who conspired with your husband in the purchase of - what is it now - 3 homes? Who ran tales on you in your dealings with your brother? Who has told what you believe to be lies about your sons wife? It's lovely now that you have a good relationship but I see so much manipulation from the past - I can't believe she went to counselling sessions with you - what is that about? There is something seriously not right here.
Please check through other replies on here and listen to your own heart. Maybe as a first step talk to a financial advisor or solicitor who you find on your own, no going to your children, and talk through your concerns. They are professionals and I bet they've heard all sorts over the years. You may be caught up with your daughter through the week, but you simply must find time over a weekend for a lunch (if allowed with Covid) or a walk with your son. Your daughter may be a single parent but you've said your son has a medical condition - her needs shouldn't outweigh his.