Gross Misrepresentation in hiring practice

I own my business, and interacted for almost a year with a large corporation to hire me and my employees, taking over my business (not buying it) and leasing my office space from me. After about 4 months of talks, this company assured me my salary, benefits and sign on bonus were approved. As well my employment contract and client arrangement contracts were fine tuned by my lawyer and them.

They also reviewed and agreed upon my employee's job descriptions, hours and earnings. I took my employment physical and did their compliance training in late Nov/early Dec with a planned start date of Jan 1.

In early Dec. at their instructions, I informed my employees and discussed the transition and new benefit plans. The last matter to be finalized was the office lease amount, which they had already been working on for a couple months in Sept/Oct (not a difficult decision since it was going to be current market rate).

I had spent nearly a year preparing for this transition and adjusting work processes, staffing, etc. to accommodate new ownership. (Not to mention stopping talks with other interested suitors.)

In the 11th hour in the middle of Dec., they abruptly pulled the deal leaving us hanging. It was not until late Jan that they informed me my salary was never approved and I should let them know if I would like to renegotiate.

Since all paperwork was going to be signed together (employment agreement, customer arrangements
and the office lease)just a formality at that point, nothing had actually been signed off when they pulled the rug out.

Obviously, this cost us not only money (almost $15K in legal fees), but loss of business and tremendous emotional distress.

Based on the fact that they told me everything was a go and all was approved (except filling in the lease dollars), can I take legal action, perhaps sue them for gross misrepresentation in their dealings ?

Thank you.