distinguish between defining and non-defining relative clauses

I am still confused that I should distinguish between defining relative clauses and non-defining relative clauses, using commas or pauses in spoken English.

I think that there are numerous cases where I can put pauses even before defining relative pronouns and then I would like to know when putting pauses before them can happen.

It is not possibe to forget which, who, that, etc and then words after relative pronouns can affect the way of putting pauses even in defining relative clauses?

Like, I know the person....who abandoned it.

I know the person who abandoned it.

Who is used as a defining relative pronoun here.

[During the conversation, when I forgot the word abandoned, it is possible to put a pause before who?]

Or when I am hesitating to say something, can I put pauses even in defining relative clauses?

Like, I know the person.....who was fired yesterday.

=I know the person who was fired yesterday.

Who is used as a defining relative pronoun here.

So my question is whether native English speakers always follow the rule that commas = pauses and I should find out exact meanings with existence of pauses between defining relative clauses and non-defining relative clauses?

I am sorry about dragging this question out but I am really curious to know the exact usage

Thank you so much as usual and I hope to hear from you again.