I see these little events as a blip. Its a long hard journey quitting SI. 75 days is a brilliant effort and you should be proud. You also did well in not choosing to go for the dangerous cutting utensils. Give yourself some credit, you have made big improvements there.

I dont know how long its been since I last SI, but I do have these little blips from time to time, as time goes on they are getting few and further between. I havent SI more than one or two times a year for the last few years. And even those events are very minor (as in banging my head against the wall once, using my nail to dig into my skin or biting my cheek, occasionally I will cut but they are more tiny scratches than anything else).

I see chronic SI as an addiction, and like addictions from time to time we will mess up. Try not to focus on the one time you messed up, rather focus on the fact that you lived your life without it for a spell, and you can again.

Being so hard on yourself (although you feel like you deserve it) will only cause more negative emotions. Try to let it go. I use affirmations everytime the self blame starts, something like "everybody makes mistakes, we learn and move on". I will repeat it everytime the blaming thought comes up and eventually it passes.

Goodluck, keep up the brilliant work you are doing. I believe everyone can learn to control this instead of it controlling you.