Break Ups and Wake Ups

I have a close friend who has just broken up with her boyfriend. For the year-and-a-half they have been together, it has been this constant on-again-off-again game. My evalutation of the situation is that she is of a codependent nature and he is of a manipulative nature. She feels worthless if there is no one out there desperately needing her at every moment. She feels helpless to make decisions for herself and then has trouble taking responsibility for the decisions she does make. He wants someone to take care of him. And we are talking take care of him as if he were a five year old boy. He requires her to be his alarm clock, his driver, his ATM, and the list goes on.
She keeps trying to break up with him, knowing that the relationship is unhealthy and is not something she can live with or would want to live with. But he keeps hanging things over her head and making her feel guilty for dumping him.
I want to encourage her that she is doing the right thing. I want to be there to help her stand by her decision, because I know that he will keep trying to talk her out of it. But ultimately, the decision is hers. She has to believe in herself and in her decision. I can't do it for her and my god that is so hard sometimes. You sit on the side and watch someone you love do something incredibly stupid and you can't do anything. You talk to them, give advice, offer a shoulder to cry on, etc. But at the end of the day, it is on their shoulders to carry it all out.
On a side note, it reminds me to be grateful for my situation. It is easy for a single person to get depressed about the fact that they haven't had a significant other in (gulp) 8 years. And I think there is a rule out there that negates any high school boyfriends from counting after you have graduated college. So that would leave me at having zero significant others. Anyways, society would lead us to believe that my life is in someway lacking because of this. I try to keep it in perspective, but it's hard sometimes. I hate to say that my friend's pain somehow encourages me, but in a way it does (that is probably really bad). It reminds me that relationships aren't all fun and flowers. They can be damaging and unhealthy. And eventually all relationships, even the healthy ones, are just gonna be hard. I guess I don't mind the hard part, I'm not one to turn down a challenge. Well, I could go on forever, but all this to say that I am really glad to be single sometimes (most of the time). If a good guy came along and was interested, who knows. But in the mean time, happiness is not found in waiting by the phone for someone to call. Happiness is in getting to know my other significant others, like friends and family, even better.