My goodness David she isn't your responsibility and you shouldn't have to mop up after her. Where is her boss? Who is in charge that she can get away with 63 sick days, 5 diciplinaries etc? I think she should be fired, she could hardly be called an asset.
You are sweet and caring...I'm sorry this is having such a negative impact on you but you aren't the bad guy here...she did it to herself. And I also buy into you reap what you sow...you offered her good advice and you cared enough to worry about her.
Stop beating yourself up...we think you are teriffic.