Praise be to Allaah.
It is not possible, normally, for a period to last this long, so during this time your wife is in a state of istihaadah (non-menstrual bleeding). So she should stop praying etc for the number of days that her period usually lasts every month, and this will be her menses, then she should do ghusl and pray and fast, and it is permissible to have intercourse with her, and she is taahir (pure) even though she is bleeding.
See also the answer to question no. 49671.
And Allaah knows best.