There seems to be quite a few threads at the moment where women are trapped in horrendous marriages because they have no access to money.
A while back there was a thread, which turned out to be a troll-thread so was deleted, but it brought out every fabulously devious, sneaky, resourceful mnetter who put forward some great ideas for squirrelling.
I remember a poster asking at the time for it not to be deleted because it could prove useful to other financially abused women (these women are often told that of course they can go, just don't expect to take the children...)
Advice I remember - do the weekly shop by credit card and get bits of cash back...buy clothes from places like m&s and get a refund. I'm sure there are loads of others that wily mnetters can think of.