I am so happy that you had a nice time with your Mom. I think that you have to take your happiness from wherever you find it, as you did. And take lots of it – often. This is how you will “charge your battery”. Otherwise you will become depleted with so much giving.
As for the other areas of your life that do not bring you happiness (ie the situation with your brother) you cannot let that situation bring you down. If you do so, it would make it only worse for your brother. Ultimately each of us is responsible for our own happiness – no one else is.
I wish that I could suggest an approach that would work with your brother, but I cannot. Yes, I’m a male, but I’m the type of male that would welcome all the comfort that I could get.
This may not be entirely resolved to your satisfaction, but don’t stop trying. Remember how wonderful love is. If love is offered and it is not accepted, love itself is NEVER diminished. In giving love you become the best possible “you” that you can become. That alone makes it all worthwhile.
-eKim