I don't now whether to feel bad, proud, guilty, or ecstatic about playing COD4 with my sister. You tell me.

First, a little background. I bought Unreal Tournament in the summer of 2000 after reading a bunch of great reviews. It was my first FPS purchase. My freshman year a friend of mine had Quake III and never even set it up online until I got a hold of it. I was hooked ever since. Soon after buying UT, I showed my sister how much of a bad ass I was/AM. She played it off and said whatever. To my amazement she started playing on her own free time. I laughed and just considered it cute, although futile.
As time went on I found myself having to kick her off after 'just one more head shot/multikill'. Eventually we played together on separate computers, with the help of phones, while I was away at college. I won, of course, but barely. I had mad lag compared to her better computer, I swear.
Anyway, fast forward 7-8 years and I find myself living in Japan with my sister half way around the world in Chicago. I try to keep in touch with my family, but my immigrant mom and dad can't figure out a computer for nothing. I call on Skype, but I'd rather play PS3 if I'm up late enough to talk to them given the time difference.
My genius solution was to buy a PS3 when I went home for Christmas/New Year's. I bought 2 copies of COD4 for $40 each, introduced my sister to it, and now the rest is history. Tonight was the first night I played at the same time with her, and half way across the world, no less.
The funny thing was throwing grenades half way across a map in front of her path to protect her. For the first time I felt like what a big brother is supposed to feel like. You see, my sister has always been big-boned. Never had to worry about her getting hit on much.
Anyway, my sister, as you can probably guess, is a little bit of a tom-boy, but I think it's cool. It helps us be a little bit closer. And besides, she's not like a big, butch softball player, so that's all good. Now I just have to teach her how to strafe while keeping her reticule on guys' nutsacs.