He deeply regretted it and cried all night because of it.
Tips
usage
为此 is a formal connector commonly used in writing and official speech. It can appear at the beginning of a sentence (为此,我们…) or in the middle (他为此付出了很大代价).
grammar
Similar formal connectors: 因此 (therefore - emphasizes cause), 为此 (for this - emphasizes purpose), 对此 (regarding this - introduces a response).