That lawyer will review your agreements, the state laws and the communications with the company and tell you where you’re at. You could all go in together for the lawyer btw if you have the same contract.
I bet that lawyer will tell you (if this is in California) that you just need to send a letter saying “cool guys, send the shares, I’ll worry about the taxes. I don’t consent to forfeiture.” But, crucially, I am not a lawyer and I haven’t read your agreements.
anyway I would not stress over this, but I would act quickly, don’t sign anything, don’t communicate with the company unt you’ve talked to the lawyer, and know that worst case you will be able to find a loan to bridge this. It may actually be a good candidate for a venture debt firm, but either way the lawyer you hire will probably have some leads.
Congrats on the IPO!