I would say that there can't be a definitive and quantifiable answer to this question. It depends on the person. You need to check how long you portray her personality in the story. A strong person may overcome the situation to be able to move on to another relationship in a few months. Actually, it would also depend on the person she enters into the relationship with. If she meets someone irresistible who also helps her overcome her problems, it would be much faster.
To be safe, any period less than six months would look odd.