I have said that I was at once relieved and made uneasy, but this expresses only crudely the overtones of diverse and largely subconscious feelings which comprised both the relief and the uneasiness. To begin with, the thing was so antipodally at variance with the whole chain of horrors preceding it—the change of mood from stark terror to cool complacency and even exultation was so unheralded, lightning-like, and complete!
Source: wiktionary