Some very good advice here.
First off, forget any romantic impressions you may have had, trouble for you and trouble for her.
Second I wouldn't call the police, I'd check yellow pages for places that work with troubled people.
Example local ad goes "If you don't get help at Prairie, get help someplace!" Someplace near where you live is a similar clinic, establishment.
Third, rather than shoving it down her throat, make her realize that non of the problems will go away until they have been pulled out into the light of day, looked at, examined, dealt with. There is a way out of this, but its not suicide, its accepting you have problems and need help.
Last, I watched a tv show once about people who tried to commit suicide by jumping off the Golden Gate bridge. The one thing they all had in common was, that as bad as their problems were, the second they jumped, they realized they were insignificant compared to the problem they had now. And in all cases that was while they were still on the way down.
There is help out there, help her to find it, and then help her to accept it.