Kiss-off letter to N-mother

Should I write "kiss-off" letter to my N-mother about why I cut her completely out of my life this time? When she tried to contact me in March my husband stepped in this time and left her phone message not to contact us anymore which really pissed her off! She played message for just about everyone in family and started drinking again (she's also alcoholic) and blames my husband's message for her drinking which of course we know is ridiculous. I'm thinking if I write her letter exposing everything she did to me for over 50 years (including sleeping with my married boss and holding up my husband and me at gunpoint), she'll show it to family members and they'll get better understanding about why I've cut her out of my life. The kiss-off letter is NOT for her benefit, but for mine.