Need Advice...

I'm 18, just turned 18 last Saturday. My girlfriend is 17, turning 18 in June. Basically what the story is that, my girlfriend always worrys about how her mom will react about everything, it's always been like this, even the littiest things, I understand this is normal but she doesn't know how to exactly "live" without her mom, is there any advice I can get? I want her to be more independent, her mom is not a really good influence and I believe her mom manipulates her also. She trys to tell her I'm cheating on her, blah blah and we broke up for three months because of that. Any advice?