Courtney Love Lawsuit -- You RUINED My Relationship With My Daughter

Courtney Love's relationship with her daughter Frances Bean Cobain was destroyed by a conniving lawyer who illegally meddled in their lives ... according to a lawsuit filed by Love and obtained by TMZ.

Love says she hired the attorney, Rhonda J. Holmes, in 2008 ... to help track down millions of dollars that Love suspected was stolen from the estate of her dead husband, Kurt Cobain.

In her lawsuit, Love says Holmes spent months on the case ... but never made any real progress because she was "too busy" with other stuff. Love also claims Holmes tried to undermine her ... by writing a bizarre, secret letter to Love's daughter, Frances, who was 16 at the time.

According to the docs .. Holmes' letter warned Frances of a "very scary conspiracy" and that evil people were out to get her. It also said, "The sooner I have your support and hence the support of your Trust Fund, the sooner I can ease this matter out of your Mom's hands."

Love says she didn't find out about the letter for two years ... and says it should never have been written -- it's a breach of attorney-client confidentiality.

But even worse ... she says ... the letter ruined her mother-daughter relationship ... by convincing Frances that her mom could not be trusted to make the right decisions.

Love is suing Holmes for legal malpractice among other things and is claiming emotional distress.

We contacted Holmes' office ... but so far no response.