What a horribly stressful situation... but you are way better off because I can't imagine how it would of been to cater to this kind of person! Not sure of the exact expression but something on the lines of "you give an inch and they take a mile"! So as everyone has said on this thread and so many others it is soooo important to clearly identify your limits and your boundaries and stick to them. I understand that you did all of this out of kindness, however you were setting yourself up to be taken advantage of, as this lady quickly realized how important this arrangement was for you!T
The money is important of course but your sanity and well being is alot more important
As for the other clients, it is time to apply the above advice to them to: set your rules and stick to them or you are only making it harder for you and your family.
Good luck.