Hey...I have a lot of experience with this...talking too much. I think it's a form of social anxiety. When there was an awkward silence, I felt the need to fill it....or, I should say, I used to feel that way. I no longer do this.
I don't know how I've evolved to become more comfortable not talking so much, but I have. I think it's just from a lifetime of self-evaluation and realizing how I have suffered from an inferiority complex and the the need to compensate too much.
Just pause and ask yourself...each time you feel the need to fill in the silences...if this is necessary. It's uncomfortable..yes, but let others take up the gaps. It's not always your responsibility to speak.
Silence is golden. Also, as I learned as an art student...less is better than more.