Maybe you can talk to your mother about how detached and loving might be a healthier way to approach your wife. Your wife is her own person and is entitled to make her own mistakes and learn from them with out anyone else comeing to rescure or fix things. That's the only way for your wife to learn what she has to learn...
Fixing, cushioning or whatever you want to call it isn't really loving behavior, but controlling...if you think about it.
If your wife wants help, she can ask for it and them you can decide to help or not...but until that request is made then fixing things(as if you could) is just getting in the way...
I'd let your mom know that you understand her requests come from a place of love and care for you and your son, but you need to give your wife that same love and care and step aside to let her make the bed she will lie in...
Just some thoughts since I've been reading up on detachment more...
M44 H46 T21 Married 16y D14 D12 Bomb 12/08(EA), (PA/Separation)1/09 to 5/09 Home/MC 5/09 to 12/09 Leaves 12/09 Files for Divorce Divorce final 6/30/10.