Self-confidence, social blocks and dependency issues. Help?

In my first post I mentioned that I am anti-social and rarely have any interest in socialising. I have a few close people, and that's all.

But on occasion I need to speak to people in order to get various things done (at some point in my life I would also like to experience romantic interests), and I cannot do so.

In order to speak to somebody in the "real" world (I don't really view what others view as reality as being real. It's just a physical shell to contain what is real so that we may comprehend it) I must be around somebody I know and am comfortable with, and even then I'm uncomfortable. If I am alone I experience a physical "block".

My jaw and vocal cords lock and I can't move them. I can't look at the person I'm supposed to speak to. In my head my emotions begin to condemn me. Telling me I'm weak. Pathetic. That they wouldn't want to speak to me anyway. That this should be simple. Everybody else can do it.

When it comes to friends, I have one very close friend who is essencially my anchor. I rely on them for the emotional support I can't ask of my family (as in typical things you just can't share with them), and become so clingy I even annoy myself (my friend assures me she doesn't mind). I am somewhat possessive as a friend. I get jealous and sulky when she'd rather spend time with somebody else (my emotions criticise me for this, too, telling me I'm annoying her, and she spends time with me out of pity).

There's no romantic ties between us, in case anybody mentions it.

But what can I do about either my blocks or clingyness?
My family and friends tell me that everybody experiences it, and I just need to get over it. That annoys me to no end. What part of I physically cannot move my body don't they understand!?

I can't withdraw from the world completely or else I start acting up. (I begin to have panic attacks at random moments and freqently pace around the room talking to my own emotions in my head)

But socialising is what causes my emotions to detach and criticise me even more...

Should I see a therapist, maybe?

Yes. You're trying to combat a severe case of social phobia with the use of a friend who is not equipped to deal with such fears. It will be beneficial to you and your friendship if you can receive professional guidance.