Rebuilding abdominal strength after rupturing lower abdominal muscles

Anyone have any tips on slowly, gently regaining abdominal strength after an abdominal muscle being seriously torn/ruptured? This happened last summer thanks to a horrible pilates place on Perkins Road who shall remain nameless and a very incompetent instructor who refused to listen when I told her it was my first time to do pilates and physically pushed me into position when I was not expecting it. $4,000 worth of MRIs and Dr visits later, I am now cleared to start exercising. Insurance won't cover PT for this. I am swimming and walking the Lakes and track at UREC in the meantime, but want to get my abs back in shape if possible. Thanking you all in advance.