Thanks for your enquiry and am sorry to hear of your plight.
As you will be aware, you tied in on the Lease for the remaining 12 years.
Unless the Landlord is prepared to disclaim the Lease (ie rip it up and allow you to leave with no further liability) which would be most unusual, your only way out would be to sell your business as a going concern or terminate your business and find a replacement Tenant to take on the remaining term of your Lease.
Either way, the normal procedure is for you to find a Buyer or Tenant and then obtain the Landlord's consent to an Assignment of the Lease (ie a transfer) to the new Tenant. The new Tenant then takes over your Lease and is responsible for the rent/any service charge.
Please note however, that if the new Tenant defaults on the rent, then your Landlord can come after you for any such outstanding rent. This principle applies to all commercial Leases and your Landlord won't allow you to assign the Lease without making such this provision is in place. Hopefully, this would never become an issue, but you remain potentially liable for any unpaid rent until the replacement Tenant then assigns the Lease to a third party or the term of Lease ends (ie at the end of the 14 year term).
The only other thing you could consider is see whether your Landlord would disclaim the Lease in return for a lump sum payment from you.
I am sorry this is probably not the answer you were looking for, but sets out the legal position.
If I have assisted, I would be grateful if you could leave positive feedback.