If I relapse, does than mean I have I failed with my recovery from substance abuse?

Start again. No, it is not a failure. Recovery from substance abuse is a moment-to-moment process, as you're choosing each moment whether or not to use. By the nature of the condition, relapses happen and are part of the treatment. You can get back with your recovery group and start again. Many have, and many do. Good luck.
Relapse. Relapse is a setback, not a failure. Do not get discouraged . Go back to your program.