When to cut and run

I have been pondering the question of how to tell when to support a friend going through a bad time and when a friendship is too much trouble to be worth it. I have been friends with a very intelligent, passionate person for the past decade. She has always had emotional problems that are (mostly) controlled by medication, but every once in a while something sends her into a deep funk, where she proceeds to lash out at anyone and everyone close to her. She has just returned to town from a long stint overseas, and I haven't really been the best of friends. It's a combination of factors, but mostly it comes down to being in two very different places in our lives, with vastly divergent priorities.

On Friday, I received an email from her, lambasting me for not calling her and complaining that she's really having problems and she's not getting any support from her friends. Normally, this would send me running to the phone to call her to make sure she's OK, but this time it just made me mad. VERY mad. Because it's not the first time she's sent me one of those accusatory "you're not a good friend" emails because it has been a while since we've corresponded. It's not like she has been trying to get in touch with me, and a friendship works two ways. I've told her before, "if you want to chat, email or call and I'll respond." But I haven't heard from her in months, and I'm the one not being supportive. She sent an apologetic email an hour later, but I'm still not sure when (or if) I'm going to respond.

On the happy side, my best friend showed me what patience can bring - she (finally) got engaged to her boyfriend of eight years! He asked her last night, during her birthday party, in front of the whole crowd. Down on one knee, ring in the box, the whole nine yards. I was so incredibly happy for her, and so incredibly touched by the romance, that I was in tears. It's something she has wanted for a long time now, and it is a joyous way to start the holiday season.