I really shouldn't speak up, but I think that Rabbeinu Guard has replied to similar inquiries in the past that this may be counted as a slip. But only this time!
Now that you realize the tactics of the Yetzer Horah, you must devise strategies to avoid such episodes in the future, Guard says. If such a thing were to happen again, chas v'sholom, then you will have to restart the 90 Day count.
(But we will not say v'hayamim hareshonim yiplu like by a Nazir. Even if someone falls, he did not "lose" all the good days that were behind him! Hashem collects, counts, cherishes each & every one!)