I agree with Sarahsweets .since you co-own you have legal rights. Your mother can put up a stink but legally you are protected. You live there. You’re an adult and can choose whom you date at your discrepancy. Your mother has no right to treat you like a child just because she co-signed. You had a moment of weakness during a very emotional time. Your mother can’t now use that against you and him. She sounds very controlling. Tell her to back off and continue seeing your beau.