How To Begin Taking Myself Off The Pristiq Medication?

I am an eighty-year old femaIe and just retired in Dec. from a full-time job. The cost of a 90 day supply of Pristiq through my former medical ins. was $100. Today, I discovered the cost of a 30- supply at Walgreens is going to cost me $257. I ve been taking anti-depressants for fifteen years. Please advise how to begin taking myself off this medication. I am going to stop all medication with the exception of diclofenac which I need for arthritis. I am not going to renew prescriptions for Simvistatin, Lisinopril and Metopropal . I ve been on these medications since a quadruple bypass four years ago and feel the time has come to stop all medication now that my only income is social security. Thank you so much for your advice, and I hope you aren t going to tell me what I already know: I m 80 and I don t expect to live forever so not taking the above listed medications could be a solution for several reasons.