living with my girlfriend 12 years in a home i am on the mort only but she is on title with me i need to break up with her due to irretrievable break

If your girlfriend is not willing to work cooperatively in either selling the house or working with you on a buyout, then you will need to file a Petition to Parition in the Probate and Family Court (or Land Court if you own registered land).  The court will appoint a commissioner to sell the real estate and divide the proceeds.  The court may also allow one party to purchase the property from the other at fair market value.  Many thanks,  Kevin Rauseo.