expression
and what is worse; to make matters worse
Used as a sentence-initial or clause-initial phrase to introduce an additional negative point, often in spoken or written narrative.
電車が遅れて、さらに悪いことに雨が降り出した。
The train was late, and to make matters worse, it started raining.
彼は財布を落とした。さらに悪いことに、パスポートも入っていた。
He dropped his wallet. And what is worse, his passport was in it.