Hi JA customer and thanks for writing.
First off, my condolences to you on the loss of your mother. I know how profound a loss this is.
Secondly, I am so sorry to hear your story. That said, I think you fairly well know what I am going to say about your current family dynamics and I am sorry that it will not be a comforting statement to hear.
Your brother is an adult and as such you have no control over his bad behavior. There is not a thing you can do to change him and any efforts you make that do not include a professional in the mix are quite likely to fail. While in your post you never formulate a question for us, I think you are asking what you can do to change him? and the response is that there is not a thing you can do to change him or his behaviors.
I know how very disappointed you are going to be with my response but it is the expert response and it is based on thirty years of seeing many families in the same situation you find yourself.
The only thing that you can do is to change the way that you respond to your brother. You say that you have tried ignoring him and not getting involved in the drama he creates and this is actually what I recommend. You do not say why this has not worked for you. I believe that your instinct is on target on this and it is what you need to do. If it has not worked thus far for you, consider getting into therapy yourself so you have someone in your life who is caring and compassionate and supports you in this setting of boundaries. What you are attempting to do is sanity preserving and life saving and I do think you are on the right track, but it is also something that is quite difficult to do and would be easier to address and accomplish with the support of a therapist.
Let me know if you have more questions on this or more information to provide?
Since you did not actually formulate a question for us, let me know if there is more we can do for you from here?
All my best and very warm regards,