Toxic friends?

[sugar and spice]

How do you know whether or not it's worth having someone in your life anymore?

Some brief background: I've been friends with these girls since basically the beginning of my time here at the UW -- one of them was even my roommate my first year here. We've had times when we were closer and times when we had more distance, but we were probably at our closest this spring and early this summer. I was dealing with coming out of a long spell of depression and a nasty breakup, and they were 100 percent there for me. I was living with two of these three girls this summer, and at the beginning of the summer we had an awesome dynamic going, I was getting my life back on track and making a bunch of new friends, just generally having an awesome time. About halfway through the summer, however, the complications started.

"Amy" has been going through depression herself, but because depression gives her the attention she craves, she's unable to pull herself out of it. (For a while she was having substance abuse issues as well but fortunately she is getting that under control.) She has a habit of demanding attention and help from well-meaning friends until she drains them of their energy and they finally have to cut her off, and then she finds somebody else to leach off of. I was one of these people.

"Beth" has major insecurity issues that lead to irrational behavior. I can't even count how many times I heard stuff like "You're the pretty roommate, boys don't like me, etc." when I was living with her. Obviously her insecurity issues mean that she puts up with a lot of isht from people that she shouldn't put up with -- especially when it comes to Amy's attention-whoring. These two feed off of each other. Also, her insecurities lead to behavior like hooking up with two guys who are friends and then watching them fight over her because she needs that ego boost -- and then trying to get me to "take her side" and accusing me of being a bad friend when I don't.

"Carly" is not as bad as the other two, but she is sort of a package deal when it comes to them and is caught up in their isht. She also has some issues with spilling secrets for the purpose of stirring the pot.

Also, I want to point out that this is just scraping the surface with what I've dealt with this summer. The rest is just too much to list! I've gotten to the point where I know these girls are just dragging me down and we've all discussed it and decided it would be best for us to "take a break" from each other. But I'm not sure that a temporary break is going to be enough because I am so worn out from dealing with them. I really like these girls, but all of that has just been overwhelmed by the amount of bullisht I've had to deal with lately. I don't ever want to get sucked back into that again.

How do you know when it's time to cut friends out of your life entirely?