<human>: Give me the gist of the text in a nutshell

A friend of mine from high school got engaged a little bit after me. She, at first, was unsure she was going to have a wedding reception, but both of us were excited that this happened to us around the same time. That said, I'm not really as close with her as I used to be (I haven't seen her in over a year and a half, and she lives not too far from me!) and her wedding date is coming up. 

Now, my wedding is set for the end of June, she invited me and I (out of guilt) invited her. But my fiance hit me with the news that he has a huge project coming up, right around her wedding weekend, and he's unsure he will be able to make it with me. 

I'm not a very awkward person, in fact, I'm a very social person, but I feel uncomfortable going to a wedding where I will not know anyone but the bride. 

Do I tell her no? How would I tell her no? I'm so caught up in this dilemma!
<bot>: Invited to friend's wedding whom I haven't seen in over a year, fiance can't make it with me, kind of sort of don't want to go because I don't know anyone, how do I say no?