SUBREDDIT: r/relationships
TITLE: Is it okay for me to visit a best friend of the opposite sex who lives out of state?
POST: My girlfriend and I are both 27 and have been dating for a little over 2 years, except for a 6 week break about a year and half ago.

My friend and I have known each other since college, and met in 2004-5. I didn't know my girlfriend had a problem with me going to see my friend. They've met, but only briefly, and she's been a part of lots of stories from college--including a story in which we kissed--in 2005.

I have a best friend who is female and lives halfway across the country.  She moved away and I've gone and seen her each of the last 2 winters.  It was brought up today that one of my other best friends was going to see her, and that I should go the same weekend. My girlfriend's reaction was "well that's better than you going alone". Even if my friend doesn't end up going, I want to go, even if it is alone because it's a long weekend. 

This is how I found out that she had a problem with the fact that I had gone the past 2 years. Needless to say, this started a conversation which turned into an argument. The conversation ended with me being mad because she's mad.  I think that she's being overbearing and controlling.  She apparently thinks that I'm going to cheat on her, or have in the past, with this friend of mine. 

I know the whole "put yourself in her shoes" philosophy applies here, but I think I wouldn't have a problem as long as I had met him and had a backstory that was verifiable, like mine.

Am I being weird, or is she being weird? I don't really know what to think and I don't want to say, "well she was here first, take a hike", but I'm kind of feeling that way. What should I do?
TL;DR: 
My girlfriend is mad that I have gone, and would go again, alone to see a best friend who is a girl and who I kissed twice 7 years ago.