Hi netforce, welcome to our community. It is very wise and also very kind that you see things so clearly and are willing to help you mother. I would suggest reading all you can about PTSD and the toll that long term abuse can have on victim, your mom will need all the help you can muster to help her see what the correct path is. It is in many ways like dealing with a person who has been in a cult for many years except with a Psychopath it is a cult of 1 with the Psychopath as the leader. I would suggest that your mom has been severely turned upside down but the good things is she did leave so there is hope with time that she will leave for good and leave him to fend for himself.
Do you think if she finds he is seeing other women that will help her to turn the corner and stop financing him?
Try to keep in mind that he is playing the victim while victimizing others so I would guess that is why your mom feels some obligation to keep taking care of him financially.
My mom had become clinged onto this man while dealing with the passing of her sister and I believe my dad who was this man had found the weak spot in my mom.
That is precisely how they operate, your mom is probably still going back in her mind and remembering when he was kind in order to not focus on the reality of what he really is.
Di