Boy Dilemma...

I forgot to mention in my last post a sort-of dilemma I'm having. My sister wants me to break up with Andy for Jack, and even though I like Jack a lot, I love Andy and could never hurt him. She doesn't really understand it. She hates Andy because he's quiet and "weird," but the thing is, Jack is just as quiet if not even more so than Andy, and has a lot of the same quirks. I think it has to do with the fact that my sister judges people by their appearances more than anything else. Like Andy has been the best boyfriend I've ever had without a doubt. He gives me no reason to complain, and even though he's far away and we can't be together as much as we'd like he brightens every single day of mine. He always shows how he cares about me, whether it's a phone call when I need to talk about something, sending me adorable pictures and videos of kittens, puppies, or other baby animals when I'm sad, sending me news articles/clips from shows or movies that remind him of me, talk about things I'm interested in, and so on. He's the perfect gentleman: respectful and kind. He never stops telling me he loves me, and I love him too. He's never hurt anything or anybody, and if I did something that hurt him I could never forgive myself. He's the closest thing to an angel that there is in my eyes. 

Still, I can't help but think about Jack a lot. What am I supposed to do? I see so many of the qualities that I love about Andy in him: both are introverted, handsome guys, gifted artists (Andy with writing, music, and films and Jack with Drawing and Painting), sweet as can be, and respectful of others. Andy knows me better than I know myself, we share the same interests, beliefs, and dreams. I don't even know what kind of music Jack likes or what his favorite color is! Andy and I have had (in about one month) two years together to build a solid foundation for our relationship. Not once have we thought, not once has he ever given me even half a reason to leave him, so why on earth should I? 
Nonetheless, I still really like Jack and I don't know what to do. I have feelings for him, but I'm pretty scared to act on them because I don't want to even consider hurting Andy or risk him finding out about it. Like I've tried voicing my feelings to people but I don't know what to do. Next year all three of us are going to be spread out across different schools anyway, so why should I try to start anything?

In case you didn't notice, I'm still a bundle of confusion and fellings and hormones.