To make it a doubly hard day for the 25-year-old, the defeat meant she also missed out on becoming world number one. Is this the beginning of a glorious career for the young girl, only time will tell but as of now she is Philippe-Chatrier's heroine, not afraid of anything.
'I think yes, ' she said. "It was always my dream, when I was a child I was watching players here".
Halep was up 6-4, 3-0, and was again up 3-1 in the deciding set, before she eventually succumbed to the barrage of winners off the Ostapenko racquet.
"As I said, she deserved to win". Ostapenko, 20, won the important points, including late in the third set.
She tore into the Halep second serve, stepping inside the baseline and attacking off both sides, and her power was simply too much for her opponent's defence. And, unfailingly in each of these five matches, her natural game looked to be much pronounced and dictated with a lot more controlled aggression.
"(Ostapenko) played like a champion that she now is, her first major title but surely not the last one", Navratilova added on Twitter. Hurts a lot, and I need time just to, I don't know.
"I will keep working, because I really want to repeat what I have done this tournament".
"I didn't see how people could play tennis on it".
The Romanian had played the percentages, with just one victor and two errors, and she looked set to end her wait for a major title when she moved 3-0 up in the second.
Playing a fearless brand of tennis with a level of danger that shares similarities with the Auckland Sky Tower jump, Ostapenko took risks throughout the fortnight here and will return to Riga with a grand slam title in the bag. It was possibly her best chance to win a Grand Slam. "And Jelena has more focus if I'm not there". "I think it's going to be a little bit hard but I chose to be a tennis player, that's my career, so I should be fine with that".
Bombarding Halep from the back-court, Ostapenko continued to land winners - but even more unforced errors and quickly lapsed to 0-3 (0-40).
Ostapenko said she was more than comfortable with dealing with her sudden fame which will be under a harsh spotlight when Wimbledon starts in four weeks' time.
The last time Canadians captures more than one title at a Grand Slam was in 2012 at Wimbledon with Eugenie Bouchard taking the girls' singles and doubles and Filip Peliwo winning boys' singles. Simona Halep's coach Darren Cahill, about Ostapenko. Three years ago it was something new.
Contrastingly, for all her inexperience, playing in what will now be forever regarded as her career-defining match, this was one aspect in which Ostapenko didn't falter, proving herself to be a champion in equanimity in tandem with the scoreline.