Girlfriend / Best Friend Problem. Really need help

So I've been dating my girlfriend for four years now. We have a good relationship and from the way I understand it, we're in love. We live about 4 hours away from each other (college) so we get to see each other around two times a month, excluding breaks. Over this recent Thanksgiving break, my girlfriend spent the time at her grandparents house quite a ways away. We hardly got to see each other.
Now here is the problem. I've had this friend for about 7 years now. You guessed it... she's a girl. We used to be really close when we first met, (hang out, watch tv, go to the movies) childish things like that. We hung out very frequently for about the first 3 years of our friendship. We even made out a party once. She's always had a very huge obvious crush on me. I mean this girl would literally do anything for me.
For some reason we began to drift apart, and hang out less and less. I finally ended up getting the girlfriend I still have now, and the hanging out with my best friend was literally limited to once a month at the most. She also ended up getting a boyfriend.
So here we are today.
Over the Thanksgiving break, I for some reason texted her to see how she was doing. She was home from college and so was I. We hung out almost every night of break. Some alone, some with friends. She's single now. From the first night of break we hung out, I began to feel something for her. I don't know why because I've never felt like this about her. She's always been a friend. I wanted to hang out more and more with her. I learned she's got a new boyfriend now. She doesn't seem as flirtatious towards me as she used to be, probably because of that. I feel like perhaps I missed out on the chance that I had, and I might regret it.

I really do love my girlfriend, but I can't get my best friend out of my head. I don't know what to do, because I don't want to risk losing my four year relationship for something that might not even happen.

Please let me know what you guys think I should do. Also, sorry for any grammatical errors. This was typed very briefly.

This won't be the first time you will run into this situation where you see, know, or work with a person that you will find desirable, but it doesn't mean you have to throw everything aside to pursue the idea. So hold off on giving up a great relationship with your gf.


Reason for it, it's because she isn't that needy, do everything for you girl anymore that you were so used to being that way....and you took it for granted actually. When you play it cool, and shut off the attention, you make yourself attractive...and well she just did that....now you see her in a new light. Your reaction to this is typical, so don't sweat it, it will pass.

hmm...have you ever seen tv series named Honey and Clover?you have pretty same story as Takumi had there...

anyway...decide first what you want...but it seems like,if you decide for your friend,its too late anyway (ofc,if you are saying that she will do anything for you,you might get her back and couse her a lot of pain)...and if you decide for your current girlfriend,im not sure if your friendship with your friend will be the same...most probably not...

..but its only up to you,who you will choose...but since your friend has a bf now...means she finaly get over it and is finally ready to move on since she saw that its heading nowhere...

But to be honest...yea,youve missed your chance.

Thank you for the responses.
Another thing I forgot to mention is that my friend and I have a lot more in common than my girlfriend and I do. Same music, same friends, same hobbies. We're more compatible the way I see it. Yet again they say opposites attract.
Another thing I did notice when hanging out with my friend a couple nights ago, we had a moment where our eyes met and we just looked at each other for like 10 seconds. I kind of wanted to kiss her, as bad as it sounds, and I"m thinking she wanted the same thing.