the walls of self control are very easy to destroy, easy to repair, hard to rebuild and very hard to build from scratch.
Hey brother in Christ, I had an Orthodox group set up and would be glad to have you around: https://forum.nofap.com/index.php?groups/orthodox-christian-fapstronauts.81/forums
I write you here so as not to occupy a thread of somebody else and stray off topic. It is true we must not judge. It's just that I am appalled to see such things. I kinda always hated most sorts of sexual immoralities even before my conversion.
My understanding was shallower, but for me fapping and one night stands or casual relationships were on the same ground, except, as you say, the sin done with other people is worse.