I'd say she's a pathological liar.

A pathological liar not only lies frequently, but may feel a compulsion to do so. Pathological liars can’t stop lying even when it causes psychological distress, puts them in danger, and creates problems with relationships, work, or other aspects of daily life.

Being a pathological liar is not in itself a mental health diagnosis. It is not included in the DSM-5, which lists mental health disorders. However, it is an established concept in psychology. Pathological lying is related to disordered thinking patterns and beliefs. The word pathological indicates that there is an underlying "pathology" or illness. Hence, pathological liar signs are associated with various underlying mental health illnesses.

10 Pathological Liar Signs:

1) Embellishing lies with extensive details 

2) Telling dramatic and highly unlikely stories

3) Appearing anxious while talking

4) Getting defensive when confronted about a lie

5) Constantly changing their story or being vague when questioned 

6) Lying about something even when there’s no reason to 

7) Seeming unconcerned with being caught in a lie

8) Feeling a “high” when they get away with lying

9) Passing off a story someone else told as their own

10) Acting in ways that don’t match their words

Source: Newport Institute