So I've been talking to a new guy recently, becoming friends and such. We talk through text and on the phone occasionally.

We met through a mutual friend. Kind of. My best friend recently moved away with her boyfriend, so the last week she was here I spent every day at their apartment. About twice when I was over there, this new guy was there because he is their friend and a co-worker of her boyfriend. We talked but never really had a conversation there. I just more or less met him.

So a few weeks after they left, the new guy asked my best friend for my phone number, and she gave it to him (after asking me if it was okay of course.) And we've been texting ever since.
And recently, my best friend has been saying that this guy is asking her about me and asking if I've said anything about him to her (which I haven't, I'm a very private person.) Basically, he's interested in me. The only problem is that I have very bad anxiety, and it's the worst when I'm around new people before I'm comfortable with them. This is even worse for me now because I feel pressure because this guy is interested in me and I'm not sure if I reciprocate the feelings.
Another problem is that my bestfriend is getting upset for some reason that he's asking her all this information and that he asked for my number. Now, my best friend and I have a history, and we dated for a while, almost got back together, and have had feelings for each other a lot. Recently I can tell something's bothering her, but she won't really say. She just says she's "confused" and when I ask her what about, she just says it's because this guy is asking all of this stuff and she's not sure why he is doing it.

I would appreciate any input on this situation. What can I do to make my anxiety better? I am very socially awkward around new people. It is quite a problem, and presents itself whenever I'm around ANYONE new. I get quiet and shy and awkward and don't know what to do with myself or what to say. I end up making a terrible first impression.
And, why would my best friend be confused about this situation when it doesn't necessarily directly affect her? Is she jealous for some reason?
Please, any advice would be much appreciated