My initial CFI was the 9 hour variety and was one of, if not the most difficult checkrides I have taken. I didn't know the failure rate was so high--maybe I was lucky? Wow. Maybe I can understand from a difficulty perspective, but 70% failures??? Wow.
Keep your head up dude. Remember this well, especially what you have learned from it--you will need to convince interviewers you have grown because of it not in spite of it! Seems you have a good attitude about it and that, is often often underestimated in this community.
No more Tacos--best of luck to you!
Philly