Need Help with commonlaw break up

[PGW]

This is my first post so I will try to be brief. This is a 13 year relationship and my 24 yr old daughter lives with us. She is a full time student who also works. He wants out pronto, wants to sell the jointly owned house and will take the first offer that comes along. I don't want to sell as this is my home, I waited a long time to own a home again, neither of us has a company pension or rrsp's, this is it. We are almost 4 yrs into a 5 yr mortgage and will have to pay a $5000.00 interest differential penalty by selling now. I just want to hang onto it for at least a year in order for my daughter to finish her last year of nursing and avoid the penalty. I would love for him to walk away without anything as he is cheating and doesn't even have the decency to hide it.We don't have large incomes and the only way the bank will let me hang onto it is if I add my daughter as co owner but I was wondering if anyone has any experience with occupational renting. If he agrees, I would pay most of the expenses, he pay a portion, we avoid the penalty then sell when mortgage is up in one year. Any thoughts or advice would be appreciated. He wants out know and rent in our city is more than I can afford, it would be about 80% of my monthly income.
Thank you