How can I change better?

I have a big problem of my English speaking.

I have met him since last Jan. I always chat with him on MSN, also I can easy express what I say on that. However, when I really talk to him face to face or on phone, I feel have a lot of  difficulties to speak English. I can't express myself, I can't ask what I want. I always make him confuse and not understand what I say. 

Somtimes I feel no confidence to speak English. When my feeling nervous, I really feel more difficult to organize my thoughts before speaking. I use wrong garmmars, wrong words, wrong tenses and so on. In addition, I think my pronounciation isn't well due to lose more self-confidence.

Therefore we usually talk online, not on phone. I think this is a bit odd because it seems to be normal to chat on phone when we are friend. Actually, I like to talk with him but I've always no topics to raise and I can't catch his meaning when he talks sometimes. I often keep slience on the phone. 

In fact I feel very anxious about this. I think this is a big blockage if I will develope our relationship.

Consequently I always think how to make myself speak better and solve my problems about self-confidence, anxiety. You know those kinds of problem which make me sleepless all the times.

Maybe I'm very silly and stubborn. 

Finally, may I ask you all a question? Does someone have this kind of problem about speaking unconsistencely when feeling nervous.

Than you all!!