Keeping those people out of my life has helped immensely. I strongly suggest you do the same as no amount of money is worth your sanity. You don't even have to rage at her... just tell her that she is mentally unstable and aging poorly... being calm and aloof when you insult someone seems to drive the knife in deeper. If she insults you back, just nonchalantly blame her for whatever flaw she accuses you of having.
Run, take up kickboxing, or do yoga.. you're right that this anger is hurting you (both physically and emotionally). You can sort through it in time, but in the meantime take care of yourself otherwise. The exertion will increase endorphin production and other "happy" chemicals that will counter the anger to a degree, so that's another benefit.
If you are religious, pray for them. I know it sounds ridiculous, but when I was the most angry and in pain, praying that they would never hurt someone like they'd hurt me or praying that God would hold a mirror to their face helped me some. It is partly a "letting go" of the control over the situation (and of course any control over someone else's actions is simply an illusion). Letting go and "giving it to God" made me feel a little lighter.
Definitely consider therapy. You suffered abuse as a child, and you need the tools that a good professional can give you. The anger is just a way of cauterizing the wound that she continues to pick at. Don't be afraid to tell those to whom SHE reaches out to get at you that she was abusive... those are strong words, but they apply in your case. Tell everyone that she was a "Mommy Dearest" (see the film if you haven't) and that on the outside she wore a mask to hide the horror she visited upon her children.
Good- solid advice- I agree. I dont believe that you need to join your mother in perpetuating your suffering. Forgive her and avoid her. It is just not worth carrying around the pain of hate and wanting revenge. I am not sure that visualising harming the other person helps long term. It can help momentarily. As for revenge, even if you actually took revenge, believe me- it is not going to give you happiness or closure. Nothing works like forgiveness. I am not saying you need to forget and be good to her etc- stop making it a cycle by returning in the same coin. You deserve better. Forgive and purge the poison in your system. Avoid and avoid getting more poison in your system. Remember- you cant control the other person- only your reaction to them can be controlled.
What is it about the money ? Are you sure that the money is going to be worth all the continued suffering that you undergo ? Cant you do without it ? Treating people good when you love them is one thing- but accepting abuse for the sake of money is akin to slavery. Do you really need the money that much ?
Talk to people, on this forum and elsewhere, try to understand as much as you can - what happened and why it happened. You have already brought up your own children well. It is time you got help and got out of the toxic relationship. Bask in giving and receiving love from people in your family who are normal.