I have experienced this a lot too. Often times I had to make the choice to SI or kill myself.
The urges are bad, but when you wait, it's worse. I really don't know what to say other than to urge you to go to a therapist (if you don't already have one), and to give you some of the coping mechanisms I use. Snapping a rubber band on your wrist, or holding ice cubes in your hand both work for me. They cause pain, but they don't leave permanent damage.
Hope this helps!