…。
Tomorrow... tomorrow felt impossibly far away.
Literal
Tomorrow... tomorrow [quotative-という] day [subject-が] far-far ahead [possessive-の] thing [like-のように] felt-passively.
A literary, introspective sentence. The trailing ellipsis (…) and the reduplication 遠い遠い ('far-far' for emphasis) both evoke wistful mood. 感じられる is the passive of 感じる ('feel'), giving a 'it was felt' / 'it came across as' nuance — the sensation is presented as happening to the experiencer rather than initiated by them. ~のように = 'like X' (noun + like). A piece of narrative prose.