MultibitHD is No Longer Supported (transfer funds without fee)
Check the average transaction fee on the blockchain right now, and then look for your transaction on blockchain.info. If your mining fee is significantly lower that average, it will be stuck there for a long time. Eventually your transaction priority will be pushed higher, but there's a backlog of unconfirmed transaction overloading the blockchain right now. If your fee was too low, it will eventually reject the transaction and it will come back to your wallet. You can't do much at the moment right now when your transaction is in a hanging state.