My question is about selling a house in germany after seperating with the co owner!!?

Right firstly I purchased a house in 2004 in muenster Germany with my partner at the time. Both our names are on the papers (and still are) and she is still currently living there with our son. I have paid the morgage single handedly (although through our joint bank account) even after we split in 2007. The morgage is not paid off. I have invested alot of money in this house and I havent taken action as of yet because of the child however i have a new wife and baby on the way and want (NEED!!!) what I am owed. My only problem at the moment is finding out what that is!!! can i sell the house with or without her permission? be bought out by my ex? what are my rights?