My Narc Sister----What Should I Do?

First let me say that my father was a N and he abused me and my sister terribly. After my father's death my sister immediately started acting just like him. It shocked me. My sister was my best friend. I loved her more than all the world. When she started beating me up on a regular basis, I turned her in to the cops. My sister has a Master's degree, is married (to a person with PTSD from the war), and has four beautiful kids and lives in a nice home. She tells everyone that I'm crazy (as if I put those bruises and scratches on myself). I never went to her graduation or wedding because she is so abusive I prefer to avoid her. Even when she had two sets of twins a year apart I never bothered to see them because as I said before, my sister is an abusive manipulative troublemaker, and will use her kids as pawns in order to get her way. A few times after my mom guilt-tripped me saying how much my sister misses me, I would attempt to reconcile with her. It always ended badly. One time my mother was driven by an ambulance to a hospital that was 500 miles away. I wasn't allowed to ride with her. My sister knows the area where the hospital is, so I asked if she could drive me there. I gave her money for gas. She then told me that she had her husband's niece and nephew with her (her kids weren't born yet), and they needed to be fed because she had no money, and it was a long trip, and they also needed a hotel room to be paid for by me. "Can't you just pack them stuff to eat from home?" I asked. She said that she didn't have anything. Anyway, because I didn't know the area, my sister agreed to meet me at a McDonalds two hours from my house. From there, I would follow her to her house, park the car, and then ride with her to the hospital. I immediately rushed to the McDonalds that was 2 hrs. away. When I got there at 11 at night, I expected to see my sister there waiting for me. There were only two cars in the parking lot. There were two workers behind the counter. I put 2 and 2 together, and realized that she wasn't there. I waited. And waited. The lights went out in the parking lot. I decided to park across the street on the road. I called her on my cell. "Where are you?" I asked. "I've been here an hour."
"I'm at Walmart buying shorts for the kids," she answered.
"I thought you had no money!" I told her. No reply.
"Just get here now!" I ordered.
"It's a long line," she answered.
"Leave the stuff, and go!" I told her. "You can buy them shorts any time!"
An hour later, she came by. I kept flashing my headlights at random strangers because I didn't know what her car looked like. When it was time to follow her to her house she drove so fast, I could not follow her just by driving the speed limit. She must have been driving 75 mph with kids in the backseat. I stayed at 55. No surprise, I lost her. That took another 45 minutes. This was one of her games. She did not care that her mother was just rushed to the hospital in an ambulance. It was more important for her to create chaos. When I finally found her, I cursed her out. She said that she didn't know what I was talking about, she was only doing 55. BULL! Then we drive an hour down the highway, and she pulls at a rest stop. "What are you doing?" I asked.
"I need my rest," she replied. "It's late."
"It's late because you took your sweet-ass time to get going! And then you deliberately got me lost." I told her. "Now you're taking even more time."
She swore at me. I told her not to use the F word in front of the kids. She then kicked me out of her car. I demanded that she pay me back the gas money that I had given her. She threw two 20s at me, and told me to get the F out. At 3 am I was alone walking on a highway where walking was prohibited (with my overnight bag, almost got hit by two truckers, I was in a strange place, and had no clue what to do. Finally I saw a hotel in the horizon, and just when I was about to go to the exit, four cop cars stopped me, and almost arrested me.
My sister told everyone that I voluntarily got out of the car, and had her niece and nephew lie for her. It was then that I realized that reconciliation with her was impossible.
That was 5 years ago. I never talked to her since until last week when my mother (who I'm temporarily living with because she's planning on moving with my sister to Florida soon. We decided to rent a big house together so she could live with me in the summer.)ORDERED me to come with her in a blizzard to drive three hours away to pick up my sister because her PTSD husband had gone insane again. "No!" I answered.
"YES!" she demanded. She then told me how she called my sister, and said that we were coming.
"I'm not coming!" I stated.
"Yes you are!" my mother demanded. "She needs help. My retirement check hasn't come yet, and I need money for gas. It's an emergency."
"Have her call the police if it's an emergency!" I told her.
"She doesn't want the kids to see that," Mom replied.
Needless to say, I filled the car with gas, and drove with her in that dark stormy night. It took four hours.
When I saw her kids for the first time, I fell instantly in love. They were two sets of twins aged three, and two.
When we stayed together at the house I'm sharing with Mom, it was fun. My sister made snarky comments to me, but I ignored them. I just loved the babies so much! She was trying to get me to go places with her with the kids. I knew her tricks. She would make ME take care of the kids while she played. She would then tell me that she wanted to visit her high school friends while I took the kids. Four toddlers exhausted me too much to take care of all by myself, and my mom is disabled. I respectfully told her no. The next day my sister informed Mom and I that she was going with her best friend to the spa. "How long is that going to take?" I asked.
She shrugged, and said, "Until both of us are done."
I decided that it was understandable for her to want some time away from the kids, so Mom and I entertained the four toddlers while she was gone (for four hours).
Then the next day she told Mom and I that she wanted to go bingo at the casino (that too takes four hours). Regretfully, I opened my mouth. "We know what that means!" I said to Mom.
"What the f-ck does it mean?" my sister snapped. "I want to know!"
"It means you went to the spa yesterday, you're going to bingo tonight! Why don't you stay home and watch the kids? This isn't a vacation! We brought you here because you needed help!"
My sister immediately ran into the kitchen where the kids were playing with homemade play dough, and screamed to them that I wasn't their aunt. She said that I was nothing to them, and they were never to talk to me, or about me. She then told them to pack up because they were leaving. (We took both cars when she came here.) The kids cried, and kept asking her what happened. It ripped my heart out when my niece looked at me so confused and hurt. They gave me presents that they made for me out of playdough. My sister ordered them to stay away from me. My youngest niece put her arms up for me to carry her. She kept crying out, "I want you!" I just held her little hands. I told the kids that I loved them, and that I was so sorry. My sister then refused to move her car when I told her that I had a doctor's appt.. I missed that appt., and was charged $25 for not showing up.
After she left, I discovered that my toothpaste that she had thrown away because it had fallen in the toilet was now back where I initially kept it. She fished it out of the trash in hopes that I had forgotten, and would brush my teeth with it.
My heart aches because I love those kids so much! Mom told her that she was doing those kids no favors by leading them to believe that their aunt didn't love them. I refused to meet them before because I knew that this day would come. I am tempted to tell my sister that I am willing to kiss her butt, and take her crap so long as I get to see those precious sweethearts! My heart is so broken. I miss those sweet babies! What do I do? She says that she wishes that I never met them. I was FORCED into meeting them when Mom demanded that I drive out there late at night in a blizzard to rescue them from their crazy father!