Your former girlfriend must still contribute for the time being, unless her financial situation changes, for example if she becomes unemployed, gets a disability pension, etc.
I do not (yet?) agree with the opinion/assessment of my predecessors to sell soon. I would like to know more about the emotional attachment to the house, the size of the house, further plans, the location of the house, your budgets, whether your former girlfriend is a civil servant, and family proximity. I also find it important to know how high your former girlfriend’s current rent is and how much rent you would have to pay if you rented a suitable apartment in an area acceptable to you.
Please do not give up so quickly, even if that was not your question. ;-)
Edit: Please no! response to the following comment: Are you sure you won’t get back together in a few months; “one” has actually seen stranger things than people getting back together after a break. ;-) (Except maybe if one of you changes their s......e orientation.)