Need Guidance

My wife in 20 years has never helped me.She's 52. I have to cook, clean, do the bills, buy groceries, cut the grass, decorate, take her to her appointments etc for over 20 years. I've never had a meal made for me, Not for my birthday, not for Christmas. Never. She constantly acts like a bratty 16 year old and I just can't get her to be responsible. A few times she's drained our bank account to give her sister money for drugs. I've had to sell our old home and move to a new city because she stopped working 12 years ago. I have no friends nor family here. I get the blame for everything. her family hates me because she makes up stories when we fight and calls them to get what i call " negative re-inforcement" Her attitude has always beem " I don't have to do anything I don't want to do" so we fight constantly about chores, money etc. I never thought that someone I've cared for so much can make me feel so unimportant. She doesn't know (or remember) anything about me. I truly feel if something happened to me she wouldn't be able to answer any question a doctor etc would ask. Everything out of her mouth is " I don't know or I don't care" . She's addicted to her tablet to the point of she believes the conversations she says she's having with 80's rock stars. As I write this, she walked out to go to her sisters  because we had an argument about her being inconsiderate. She's done this dozens of times in 20 years. For a time her threat was "I'm leaving" each time she didn't get her way. Of late it's " I'm killing myself" because i yell at her because she didn't do her chores or find out our bank account was hacked. 

Am i stuck with this? As usual she disappears for 3 days and then just shows up saying she's packing her things and leaving. I remind her that her sisters have families and you can't just walk into their lives and disrupt it. That's when the I"m killing myself comes into play. 

I don't know what to do anymore because i'm so sick of being angry with her. 

I don't understand how someone can consciously not help someone who has done everything for them in the last 20 years.