I have PMI on my property (second home) that I have problems paying for.I am already several months delinquent?

Does PMI covers only a primary residence or any property that has PMI coverage. Also I stopped paying the PMI premuim at the same time I stopped paying for the mortgage because of financial problems, is it still active even though I am not paying the premuin now. The premuim for the PMI was added to my mortgage payment so when I stopped paying the mortgage, the PMI premuim was also not paid at the.same time. Does PMI pays the lender only when the property is foreclosed or short saled? If the PMI pays the lender, does it mean the lender will not go after me for any deficiency in a short sale or foreclosure. How will I know if they will pay the lender? Thank you for your answers to my questions.