May be different here, but I very much doubt it - get it signed off legally or she can come back on you later if she starts feeling that you were unfair at some point in the future. I've had friends who thought everything was sorted fairly, to everyone's satisfaction, then a few years later a lawyers letter demanding more. Better to spend a few dollars (pounds) and be sure that cannot happen.
There's legalese stuff that if you leave it out/get it wrong on a DIY job, you basically got nothing.
Bah :( sorry to hear that!
Sounds like you've had the most useful advice already, so I'm just here with manly consolation. And drinks, if we somehow meet.