jodie34, grief can feel very overwhelming. But talking about what you are feeling, either here, or in a bereavement group, or with a counselor, can help. Don't hesitate to go for help or to ask for help if you need it.
I noticed that about your mom you said:
Quote:I have to let her go
And, similarly, about your brother:
Quote:I have to...let him go
But you don't have to let them go--in the sense that they will completely leave you. They will never leave you. They will continue to live inside of you, in your memories of them, and in your love for them. They will always be a part of your life, and a part of you, in a very real and meaningful way. Absolutely nothing, not even death, can take that from you. When you need them, you can call upon them. If you need a laugh, remember how your brother made you laugh. If things are getting you down, listen for your mom's loving, caring voice inside of you. Her love for you is still inside of you, just as your love for her lives on. Some forces are stronger than death, and love is one of those forces.
You couldn't "let them go" even if you wanted to. Allow them to live on inside of you, and allow yourself to be comforted by their loving presence there.