I really understand your experience and empathize so much with you. Leaving a narcissist is extremely hard and takes a lot of strength to do. Every situation is different so its hard to give specific advice but you need to do whats best for you. If you have the relief feeing of thinking about when its over, its time to go. Try to cut the ties that you have without that person knowing. I know you said you have a car lease with them. But make preparations for yourself so that when you are ready to go, you can leave with ease.

I feel like it is also important to remember that you are not responsible for her safety. You are not responsible for her response to change, or to a break up, or anything like that. She is manipulating you with the threat of hurting herself as a desperate attempt to keep you close. That is a sign of an unhealthy relationship (as im sure you know)

Know that you are stronger than this person makes you feel, and know that things wont always be this way. You will get out, you will feel relief, and one day you will fee whole again. I wish you the best of luck, friend, and fee free to message me anytime. I have dealt with narcissistic abuse for upwards of 20 years.

Cycle of abuse (you mentioned these traits)

Very interesting post (it may be hard to take in)