Hi Ashlee,
I really feel for you I had upheavel like you are going through. Like Vivek ananda said to see someone face to face would be great support for you going through this; there will be the support go to a doc for a referral.
(I didn't seek advice when I went through this (as I didn't know what 'this' was), quite a while ago and dealt with it by trying to escape with friends and going a lot. I was very confused about the relationship with my mom. As I had no idea what moms prob was, I didn't know where to seek help. I just knew I wasn't nuts.)
It's really important you don't loose yourself to all this mayhem, so you can reach your potential and be the person you deserve to be. This is a lot of pressure on you. I can sympathesis with you having the parent feeling, it's very odd.
Another point to consider; if a person is brought up with a borderline or NPD they run a risk of dating partners with these chracteristics; the exposure you have had will make you patient and forgiving to the problems of these disordered individuals. giving you more patience than you should for the rubbish.
I am a 'non', confident adult however my dating history from college years onwards; 1) borderline, 2) borderline 3) NPD. Suffering a number of abusive work situations also. I have done a ton of reading and now trusting my instincts that were there all along, I always went against them.doh.
Is there any chance that you and your sister can join your dad? whereever he may go. I have a feeling that once he's gone she could still be a problem for you girls. You will still have a relationship with your dad and she may take this out of you.
I would get some good literature. I haven't been on this site long but I have already seen good texts that are suggested, obviously don't let her find the book for chuffs sake. Get to a point where you really understand how she ticks so then you are the one that has control. Watch out for narcissitic supply: read up about this = When the knife goes in when you are least expecting it in retaliation for a remark that you didn't think was the least bit offensive; 'Trending on eggshells'. You are prob already aware but she is highly insecure. Maintaining her ego at all costs. Let what she says wash over you, she is ill, never forget that. It helps me to remind myself that mine is mental, that she can't help it. Like I'm a carer in an old peoples mental home. just smile on the inside when she trying to gain 'supply' of you.
I have a good relationship with my dad better than if he'd stayed with her. & you WILL come out of this! and discover the amazing strong person you are, more and more. Very important to NOT let your experience allow you to have patient with anymore lunatics though. So your life is yours and how it should be.
This is a good resource
www.lightshouse.org . It tell you about parents types etc... . takes a bit of wading through but good info in there.
All the best with this, missful x