I just don't want to have to deal with this any longer than I have to because I seem to be the only person who's trying to sort it out. No one is helpful and no one seems to know what's going on.
Thank you for the back ground, I find based on what I've read on here that it important to have context. You sound very sensible and so does your brother. Sometimes one comes in a certain order in a family and has to sort things out. In this case it's you and you seem to be doing a fine job and have very valid and logical reasons for selling the house. And your situation is most unfortunate at such a young age.
I am sorry that you feel there is nobody to help you. But you can reach out on here for financial advice. Selling the house sounds wise, the EA was unprofessional, send an email and insist in a reply that they are terminating the tenancy, if they don't reply you might have to threaten reporting them to their professional association, but hold off on this for now, it may not be necessary. Be polite but insistent in getting respect back.
Do you wish to have advice on what to do with the money, there are many sharks out there, and cleverly disguised ones at that, even bank staff are not to be trusted. There is a forum on here with the best places for deposits. You need to educate yourself on the financials so that's a good place to start.
If I can offer one piece of personal advice, don't let this period of your life affect your relationship with your brother, when you both are a bit older you may get on a bit better and no doubt you've come through a stressful situation, so best advice is to let things go. You do not know what is going through his head or how all this is affecting him.
( I wasn't much older than you when I became a landlady but it's not for the faint hearted)