In-press article, what happens if I don't pay the fee
Can anybody recommend me what to do?

Apologize and retract the paper.

What happens if I don't pay the fee?

Your paper will not be published by this journal.

Will it affect my chances of future publications in other journals of the same publisher?

Probably not.  I doubt they track this behavior.  Many of Elsevier's journals are edited independently, and will not care about a mistake made in a different journal.