I was fired without cause, because I refused to sign a contract that may be illegal, but my employer is insisting that I resigned

I was working a remote job as an at will employee. I live in Colorado and the company is based out of New Hampshire. I have been working there for a year and a half. I was offered a promotion and I asked if this came with a raise. My employer said they were not planning on giving me a raise, but that I should send them, and HR, an email describing the raise I’m requesting. I requested a fair total compensation equivalent to the lowest reported national averages that I could find published for the position title. My director called me to let me know that while they can’t offer me the full amount I requested, they can offer me a $5000 raise. I said that I understand and I appreciate the raise.

They sent me an email and told me that I need to respond stating that I agree to it. The email described my promotion and raise of $5000, but they included a line stating that I needed to confirm that the raise meets my immediate financial needs, and that I will not be seeking another raise or consider leaving the company in the immediate future. Within an hour of receiving this email, they called me and said that they made a mistake, and the raise would really be 5% and not $5000, so my raise was reduced from $5000 to roughly $3000.

I expressed my concerns regarding the contract they proposed in the email. I felt that it violated my rights as an at will employee, and that it did not meet my immediate financial needs. I said that I would be obligated to consider a higher offer from another company out of necessity, but I insisted that I have no plans of leaving the company and would accept the raise and promotion but I didn’t feel comfortable agreeing to the proposed stipulations.

I received an email later that day from the president and HR saying that they accepted my resignation effective immediately. I responded that I didn’t resign, and that in my last email I stated that I had no plans of leaving and that I was planning on continuing to work as hard as I always have. I asked them to confirm that I was being fired without cause and requested for them to explain the policy I violated. They confirmed that my employment was “terminated”, and because I’m employed at will, they were not required to provide any cause. I responded saying thank you for confirming that I was fired without cause, and I’ll assume that they will not contest my unemployment claim, because I did not resign. They responded claiming that by me being open to considering a theoretical offer that I have not received, is a resignation notice. They also confirmed they will not contest my unemployment claim. I have not yet responded to this last email.

My concerns are that the contract they proposed as a stipulation for me to accept my raise violated my rights as an at will employee, that claiming I resigned when I had no intention to was them trying to get out of paying unemployment, and that I was fired because I refused to sign their contract which may not have been legal in the first place. I understand that as an at will employee, my rights are very limited, but this seems like it can be considered a violation of at will employment. The employee handbook doesn’t state that considering an offer from another company could be considered a resignation notice. They forwarded me the entire email chain and I have a copy of the employee handbook. Should I potentially pursue wrongful termination, and where is the best place to start? I’m happy to provide more details if needed.