Ouch. I don't think there's any "easy" way. If she has that kind of baggage she needs to deal with it on her own through therapy or whatever. Your only responsibility is to be as kind and supportive as you can when you let her know its over. Maybe try to talk about the things you feel you need to head towards and don't emphasize any faults you may have seen in her.
Maybe it will help if you call her a day or two later to see how she's doing and do so on occasion after that so she doesn't feel as abandoned. But be careful in case she thinks that's a signal you're still interested.