Its like feeling my way through a tunnel of darkness
Going through a tunnel where I could not see the end
I could not see the light at the end
直訳的に表現するなら it's like feeling my way through a tunnel of darknessになります
ですが英語では手探りで道を探すよりかはゴールが見えな表現の方がよく使われます。
なのでI could not see the light at the endの方が伝わりやすいと思われます