You said basically the same thing back in February of this year
http://forums.psychcentral.com/psych...evastated.html
I don't really blame your T for getting annoyed about no payment, as its been 6 months (probably longer, since you said in that thread that you were already not paying) and now you are helping out your mother.
If you cant afford therapy for the long term (and I'd say 6 months is definitely long term) then you need to sit down and have a conversation about it with her.
It doesn't sound like malpractice to me, but I do think she could have stricter boundaries and be able to bring up the subject of money in a more sensitive way.