I don't use Multibet HD by myself. It seems Multibit HD doesn't support export of private keys.
User
nullc on Reddit says this:
But multibit uses BIP32 public derivation. This means the private keys are not actually independent. But it allows third parties to generate more keys for you without knowing any private information.
There are currently
51000 unconfirmed transactions. With your fee (0.1 m
BTC) it should confirm at some point, but it can take quite a while. I guess you're in a rush?
If it's not possible to get the private keys from Multibit HD, I can't double spend it.