Sounds like you are experiencing some transference where your therapist is behaving just like your mother behaved. Transference is typically partly about our stuff (your past experiences with your mother) but also partly about present stuff too (his talking so much is the trigger for the transference).

I think that it is possible that your therapist is talking in an attempt to put you at ease. Why do I say that? Because my therapist used to talk a lot too. And I'd feel a bit annoyed with that. Just wished he could shut up, actually, and listen a bit more. Turns out that he was trying to talk in order to prevent what he thought I would perceive to be uncomfortable silences. I told him that I'm alright with silence, though. Now he shuts up a hell of a lot more and said he would sit there in silence with me all session if I would find that helpful.

Might be that your therapist isn't so sure what to do. I guess the only way they know is if... We can somehow... Find the courage to ask / tell them.

Letters / emails can be a whole heap easier than talking. Sounds like a considerable risk (that your mother was unable to receive well). Will he be a good therapist for you??? Depends how he responds to your disclosure, I guess (will he respond similarly or show you that he is stronger than that???)