My mother is a manic depressive, she has been diagnosed as such...well...all of my life (22 years).  I have recently realized that I need help in understanding how to deal with her.  It's so stereotypical, but every couple months it seems, she goes "crazy".  She was on prozac for 20 years, then she recently switched to Paxil.  Her moods have gotten entirely worse.  Now I'm at the point where I'm either going to cut her out of my life, hate her, or hate myself.  All she seems to do lately is try to hurt me (mentally) and make me feel like I'm the one who did something wrong...and I end up thinking I need to apologize, but don't know for what.  I really need help coping and don't know what to do or where to go.  Please help me.

Troubled
 

Dear Ms. B' -- 
Unfortunately, you're in a position that is extremely common -- though that doesn't make it any less difficult.  In general, you have to establish some sort of boundary that keeps you safe, and hopefully keeps you from repeated injury enough that you don't have to just end your involvement with her entirely.  This situation is fairly analogous to the situation of a person who is married to an alcoholic, one who hasn't recognized her/his problem -- and thus arose an entire organization you probably know of, "Al-Anon":  a group for people who have a relationship to a person with alcohol problems, but don't (necessarily) have one themselves.  There might be some value for you in attending such a group, if you can find one, to see what they are saying generally.  

However, a more direct route might be to get yourself a therapist.  At the very minimum, it may help a great deal to be able to talk out loud about what you're going through.  Psychotherapy is largely just that, and it helps a lot of people that way.  Then, a good therapist may be able to add yet more value on top of just listening well:  she or he may be able to help you see the situation in a new way (so-called "dynamic" or "insight-oriented" therapy), or help you structure your way of dealing with your mother so that it is not so painful ("cognitive" or "behavioral" therapy) (and "interpersonal therapy" would also be appropriate, which is the other main type of psychotherapy out there that's been shown in research studies to be effective).  Here is a resource that might help guide your search for a good therapist.  

Dr. Phelps