I don't mean to seem gauche or insensitive, but people are always as happy as they can be in whatever circumstances they find themselves in. If you try, you can find pictures of smiling kids, even though they has distended abdomens from lack of food. The fact that a person is "happy" is meaningless. Are they living up to their potential? THAT's the question. (Or is it? I don't really claim to know.)
Your friend will probably not respond to factual information you provide for her. Her attachment to her religion is an emotional one, and all the "logic" surrounding it is just window-dressing. I know, because I did it too. There is endless discussion on this board and elsewhere about what it takes to wake a person up to the reality of the false doctrines taught by JW's. There isn't any answer though, because it isn't a fact-based belief. It is a premise-based belief, that being that the Governing Body dispenses what Jehovah expects the flock to accept as "truth". If it turns out not to be true (and only the Governing Body can make that determination), then they change it, and it becomes the new "truth".
Defeating that premise is the key -- but it's a vicious circle. They say it, and thus it's true. Since it's true, it's true. Unless it's false, and if it were false, they'd tell us. (Head hurting yet?)
Yes, if she got out of JW's, she'd have a better shot at a "real" life. No, if you stay with her you will probably not have a great relationship. No, she probably won't leave JW's no matter what you say. Yes, you should probably try. :-)
There is plenty of info here on this site and all over the internet to help you build a case. Your best bet is probably to pick something small and ask her about it. "What's this 'Beth Sarim' place that I heard the Witnesses built?" you might ask her. She probably won't know what you're talking about. Google it, and you'll know. Then you can tell her, and she can ask around and find out what their answer is. (They always have an answer). Then you can ask about some other little point. Then another. Not abrasively, just out of curiosity. You might trigger something in her -- you never know.
Good luck!
Dave