I'm very sorry about your brother Ipangel. This is a difficult situation. I was the always the "helper" in my family too! I see nothing wrong with buying the food and dropping it off, if it eases your mind. However, at this stage of your recovery, I would not get caught up in the drama. Sometimes its best to step away and "save" yourself.
One of the hardest things I had to do was let my family go. They were toxic to me. I turned to alcohol to cope with them. (I take the responsibility for drinking) I got to the point where it was destroying me. Is it hard? YES, but I am 13 months sober! So, my advice, for what its worth , is take care of yourself! They will survive without you and you can work on saving your own life. Of course, you know what's best for yourself.
Best Wishes To You!