If i stop paying mortgage on my house "what will happen"?

You will be in default. This will effect your credit and the bank will call you for missing payment. Call your lender and tell them why you cannot make your next payment. They say the lender can help you to fix your rate down to 2%, extend the terms of your loan, and may even modify your principle if you fit criteria ie. a freddie mac or fannie mae backed loan, etc. At some point, you will have to contact the lender if you cannot make payments.