Why feel shame? At least you tried and you know why you weren’t able to complete it.
In my opinion it is sometimes better to bail on a workout than forcefully finishing it and depleting the spare energy you have at that moment. I think your body can gain more from a bit more rest at that point than what it can gain from finishing the workout (especially if you run out of energy half way through).
I used to be bummed out when an exercise didn’t go as well as I thought it would, but now I just try to figure out why that was and improve on that.
That’s also part of training and getting better, it’s not all just legwork on the bike in my mind