But whatever the true explanation of Barrymore's movements might be, I felt that the responsibility of keeping them to myself until I could explain them was more than I could bear. 

请教老师: 宾语从句中，the responsibility of keeping them to myself until I could explain them 整个书宾语从句的主语吗？如果是，

until I could explain them 是修饰keeping them...的时间状语吗？ 只是整个句子的意思有点拗口，不知道怎么翻译为好？