She gets the needing to let go, and picking up the pieces when DD gets back, it's more that ... how does she, herself, stay sane? She's been to 2 psychs - one saw her 3 times and said there was nothing to do for her depression, and the other one she's seen twice now just says she needs to do something with the ex.

How does she "let go" Inanna? Is there anything that works for you, anything I can pass on to her (other than joining BB) to help her attain the peace she needs?
Just on this point, find another pych or counsellor! It is not about "doing something with the ex" its about learning to cope/deal with the ex. He will always be there and he will probably always be the way he is unless something dramatic changes, she needs to find someone (and they do exist) that recognises the difference between dealing with an ex and living with the fact that this is the way it is and helping her to live with that...

gosh does that make sense? I hope so.