I just looked at the transaction at blockchain.info and blockexplorer.com. Both can't find the transaction and I strongly believe, that I mistakenly send the transaction to a non existing adress...
That is not possible, Multibit would not allow it. Rather what likely happened was that the fee was too low so that many nodes and the block explorer nodes did not accept the transaction.
Would the raw transaction text help you and is that something that I can share openly here?
Yes and yes. The transaction does not leak private information, it is meant to be shared by every single node on the network.