Yours is not the 1st Zimmermann that has fallen to bits.
This appears to be a re-occuring problem that has been discussed multiple times in another Forum.
If I understand this correctly then it is the pipe itself that fell apart.
If so then I would say that this is a clear manufacturing fault.
Cut your losses and put on a 2 piece Hatory muffler and use the support bracket that comes with them.
Expensive but end of problem.
Unless you can get the original one repaired as suggested by Furyicon