we need to know what was being donated, and who were the donors.
There are two sentences (or two clauses) in your text.
It needs a period or full stop. Or maybe a comma.
1) with period/full-stop
"There's no way I could have gone on for as long as I have. If I'd stopped feeling for my donors every step of the way. "
2) with a comma
"There's no way I could have gone on for as long as I have, if I'd stopped feeling for my donors every step of the way. "
It looks like somebody is being donated an organ or something medical?
The recipient was able to carry on, because they felt something for the donor.
However the same could apply to any recipient of any kind/type of donation.
An alcoholic could receive donations and fell for their donors.
The sentence does not give us enough context to work with.