The passage of time is often the best indicator of whether someone is experiencing infatuation or love.
At first, the person may not really know which one they are truly experiencing as both can be very similar in the kind of emotions that they cause.
However, again, the passage of time is often how you will be able to tell whether she is infatuated or in love.
Infatuation often causes incredibly intense feelings for someone else at first but it is often short-lived and fizzles out.
It is more so based on raw emotion than a solid foundation of trust and understanding that has built up with that partner over time.
This is why it is often short-lived.
A typical period of infatuation can last a few weeks to a few months but rarely goes beyond six months.
Once the breakup happens, there is a good chance that she would go back to her toxic ex boyfriend because that is where her strongest emotions lie and the infatuation was merely a brief moment of intense feelings.
However, if she is in love, there is a higher likelihood that this relationship will last longer.
She is not going to want to go back to her toxic ex boyfriend and will do everything in her power to keep him from contacting her or reaching out to her.
It would be as though she has started a whole new life and the energy that she gives off as she goes about her daily life will reflect that.