LeAnn Rimes -- She's NOT In Rehab

LeAnn Rimes is NOT in a rehab facility ... TMZ has learned, although she's dealing with a severe inability to cope with anxiety and stress.

We had our doubts when we were initially told LeAnn is not in a traditional rehab facility -- we were hearing she was being treated for drug and eating disorder problems. But after making a bunch of calls, we're confident -- LeAnn's decision to get help is limited to coping issues. That doesn't mean she doesn't have other issues, including weight, but that's not what this is about.

Our sources say ... LeAnn has been in meltdown mode recently over a war she's been having with a group of people who are upset about her relationship with Eddie Cibrian. The group has gone after her in a big way on Twitter, and LeAnn -- rather than ignoring them -- has fought back. We're told the stress has been unbearable for her and she wanted help.

As for the kind of help ... our sources say LeAnn is in a facility that teaches people to handle adversity and stress. She is free to leave on weekends -- something that doesn't happen in rehab. She's also allowed to use her phone at any time -- again, that just doesn't happen in rehab.

LeAnn will be going home this weekend ... sources say and she's telling people she already feels stronger.

Like we said ... we initially thought LeAnn's party line was B.S. .. but now we know it to be true.