parse method

 private Map<String,Set<String>> parseCsv(Integer numRecords){
    //csvFile is public Blob member variable...
    String csvData = csvFile.ToString();
    csvData = csvData.replace('"','');
    List<String> records = csvData.split('\r?\n');
         
    Map<String,Set<String>> ans = ...

    //Start at 1 to skip header row
    for(Integer i=1; i < records.size() && (numRecords == null || i <= numRecords); i++){
      String [] columns = records.get(i).split(',',-1);
      String accountNum = columns[0];
      String name = columns[1];
      String eligible = columns[2];
      String reason = columns[3];
      //Do other stuff
    }	
    return ans;
  }

sample file

Col1,Col2,Col3,Col4^MVal1,Val2,Val3,Val4^MVal5,Val6,Val7,Val8