I wondered what comments I'd find - the ones I found made my day! Make that decade :-) Thankyou very much for them and all the support I've felt.
Calistoga, I was VERY tempted. DH being so against it is what stopped me and I'm glad now. I think it would have turned the emphasis away from MIL being in the wrong onto me doing something destructive. My point would have been lost.
blue2000, I think she was the one her family picked on. You're very astute.