I Work in a Drug and Alcohol Rehab and I Have Been Here for 3 Years. It Is a Non Profit Organization and It Is?

ran very poorly in my opinion. My title is triage. My boss has recently added a bunch of new jobs to my work load… none of which are in mt job description. My question is this I am considering quitting because it is getting to be too much for me. How would I go about talking to her before I make such a drastic decision? What could I say to make her understand that I am burnt out and my load is too much for me??? Any help much appreciated.