Hang in there and remember this feeling. Resist the chaser effect. It's not true that 'one more won't hurt'. It all affects your strength and your behaviour in future. Every second is progress.
This reddit post has a great thing to say about relapsing. https://www.reddit.com/r/NoFap/comments/2bysad/as_a_girl_i_also_see_my_boyfriends_efforts_results/