I wish I could give a definitive answer; unfortunately, it is a complicated question. I have found when dealing with people with mental illness, that they often do claim that they have forgotten their bad behavior. I do not know if I believe them, but I do know it is common. As far as is it still a toxic relationship, that depends on a lot of factors. How does seeing her make you feel? How does she treat you? How do you feel after you spend time with her? Is she limiting your relationships with anyone else? The questions could go on and on. These are just a few to consider. I believe as long as you can maintain a healthy outlook on yourself, and she is not currently negatively impacting you, then she may be no longer toxic for you to be around.