Enabling is doing for others what they are capable of doing for themselves.
I guess at this point, I'm thinking that you are now financially providing for both your Mom and your brother?
It's time to set some real boundaries for yourself.
You mentioned (I think in the other post) that you feel used. Well, I'd venture to say that it's because you ARE being used.
Your daughter can't stand your brother. I'm betting that this is really causing some major issues in your marriage as well.
I think that you need to really decide what you want - what you are willing to accept and not accept - set some boundaries - and start living YOUR life for YOU!
Each of you are responsible for your own decisions, thoughts, and feelings. And seems to me that you are carrying most of the load when it comes to the "responsible" word.