I'm sorry you're going through this, I relate very much with what you're going through. I am a complete wreck when it comes to talking to guys in person, even when he is just a friend, as well. Sometimes even talking to a girl makes me nervous. I get so nervous and can't think of anything good enough to say so I just mumble about silly things and nothing worthy comes to mind even though I have interesting things that I could discuss in the back burner of my mind (...far far far away and unreachable at that moment).
I usually tell myself to do less talking (weirdly enough), so to not pressure myself to say something so that I don't mumble. I tell myself to let the other person talk and ask more about the other person's feelings about something. People won't even notice it, as generally people like to talk when they're asked something specific. I don't know if that's in any way helpful.
I personally have never dated though. I am 23 and have zero experience with guys. (I am not exaggerating when I say zero) I'm ridiculously shy when it comes to dating or any guy advances, and feel that I can't control it. I understand the feeling of wanting a relationship, as having someone very close and intimate can be very comforting especially when you are alone most of the time. To be honest, I am in a long distance relationship right now, and I have to say talking with someone who isn't close to me, which would be very scary, has helped me a lot. I'm able to discuss anything, be silly, and just be myself. It does help a lot if the other person understands you, is honest and down to earth and knows your anxiety issues or is even familiar himself with it, as in my case. Sometimes though the long distance thing can cause anxiety itself when the other person is having a very bad day and you feel like you want to be there to comfort him. But anyway, there are pros and cons I guess, for me the pros outweigh the cons as I'm painfully awkward in person, but now I feel that if we met I wouldn't be awkward at all after talking away almost daily hours and hours for a little less than a year. I'm just saying this is a possibility, if you'd ever care for that kind of thing. I'm kind of weird.
Anyway, I just wanna say that I relate and I hope you find someone who understands you and who you can share quirky and a little awkward moments with and not feel too bad about it. I think you are very brave for going into the dating scene despite your fear and trying to overcome and cope with your anxieties and phobia, hope it will get easier.