No way around this, girl, you are being used and abused!
If your "friend" only whines and complains about her life and doesn't have the decency to at least ask how your day was, then that ain't no friend!!! This relationship did not started out like this but it will not revert back anytime soon.
You need to stay away from this person. Ignore the calls, try to avoid the places she hangs out at. Do what ever it takes - stay away from someone like this!
Start practicing different excuses. Keep them simple and straight forward.
"I have been working like crazy." OR "I was out running errands and lost track of time." OR "I've just been so busy, you can't believe!" Let her vent a little then tell her you have to go!!! Come up with anything but get off the phone. If you run into her somewhere, keep it brief... Tell her you have to go somewhere. Either way just Go...
Start out with just a couple of days at a time. Then work your way up to a week and so forth. This will not be easy but it will be worth it. The day will come when she will go off about the lack of attention she is not getting, and this is were you want to be. Very calmly and straight to the point tell her exactly what you stated in your question. "It doesn't help that she never lets me talk about Anything... Her negativity has drained me of all my life AND makes my day Worse!!"
The only way this will get better for You is to keep away from her!! And if you ever doubt why you are doing this, think back to all the times that she wouldn't give you the time of day, if it didn't concern Her!!!
With friends like that who needs enemies...
Good Luck