From personal experience about it, when I was doing streaks I could only last so long and when I eventually gave into the urges I felt like I was a complete failure, I felt guilty for my family and friends and overall just disappointed with myself. It would spiral me downward for the next several days/weeks for just 1 session of self harm. The pressure made it all seem so fucking serious so "destroying" the streak really made me feel shit.
Now while I still do it and perhaps a bit more so I've been able to find a way of dealing with it much easier. I don't put the pressure of a clean streak on myself, if I self harm that blows but I try my best to just immediately move on. If I self harm right now that would only mess me up for a single day instead of the weeks I could lose due to feeling so shit.
Of course I don't want to give the impression that I understand exactly how you're feeling or that it would help you but I really do believe that the pressure is a really bad thing to put on top of something that is already bad enough on its own you know?
If you do it, not a single person in the world could blame you for it because they have no idea what its like to be you in this situation. Feeling guilty for struggling is not something anyone should do (easier said than done lol) and I'd hate for it to make your mental health even worse than it is now simply because of the pressure and guilt the streak might be bringing.
I hope that makes sense, I''m very tired so I might be stumbling my words a bit.
Either way, whatever happens I'm proud over you and I hope that you won't beat yourself up for feeling like this and having these thoughts