Any tips on how to deal with this woman?

I'm usually pretty good when it comes to people, but my boss is a pain. She's emotional and can be bitchy and a bit vicious at times. I have worked with her for years and I have found her difficult at times but the older I get the harder I'm finding it to tolerate her. I know she has her personal problems but we all do, sometimes she just doesn't know when to shut her mouth and she has offended and upset me in the past. She's always sorry but it doesn't stop her. She winds me up, I just want some advice on how to keep my cool with her, I have erupted with her before and I don't want her to get to me like that anymore. Any suggestions?