(((((((((((((((((hereiam)))))))))))))))))))
Good for you for resisting!! That shows so much bravery, and it can be so hard...
I used to cut as well, but then my parents found out. After that I had very little trouble resisting urges to cut simply because of my parent's reaction--it was the most horrifying thing I've ever been through. I mean, when your mom is holding you and sobbing, "where did I go wrong," it makes a bit of an impression. >.<
I'm not sure if that will help you at all, but instead of imagining the consequences to YOU way in the future, imagine the REACTIONS of others who love you when they find out.
If imagining things doesn't help you or is starting to get less effective, just get out of the house or wherever it is that you SI, or away from the situation that's triggering you. Sometimes if you leave the place where SI feels "comfortable" or "okay", it can help you realize that it's not. Just take a walk, go to the store/mall/etc., or wherever.
I really don't know if that'll help you in the least, but the main thing is to stay strong. You've obviously done an incredible job of that for the longest time, so I know you still can.

Good luck!!!
yours,
~muse