horrifying:making you feel extremely shocked,disgusted or frightened
frightened adjective,(of sth / of doing sth);~(to do sth);~(that ...) :afraid; feeling fear
terrified adjective~(of sb/sth)~; (of doing sth);~(that ...) ;very frightened
scared adjective~(of sb/sth);~(of doing sth);~(to do sth);~(that ...) :frightened of sth or afraid that sth bad might happen
综上horrifying程度最大,其次为terrified（参考牛津高阶英语词典）