Need help.. terminated after giving 2 week notice so my employer could get out of paying unused vacation time

On April 15th I submitted a written 2 week notice. After submitting my noticed I reviewed our company handbook which we were required to sign. In the handbook it stated if an employee provides a 2 week notice they will be paid out for any unused vacation time, however if an employee is terminated they forfeit their time. I wrote an email to my boss and office manager to make sure I would be paid out for my unused time.
The handbook states after 1 year of service and employee is entitled to 5 days of vacation and after 2 years of service an employee is entitled to 10 days of vacation. Vacation time is determined by an employees anniversary date of hire.
My anniversary date of 2 years was 1/2/16. I received a response back that vacation time is accured and that I only had 1 day left( I have not used any of my vacation time since my anniversary date. I stated that our handbook did not state anything about accured time that it just stated we received days based on anniversary and we were never told our time accured. My office manager told me to speak to my boss on Friday . On Friday I sat down with my boss and he stated that just because I am entitled to 10 days as of 1/2 that I am not entitled as of 1/3 to take 10 days off in a row, I asked why but he didn't have a reason and said he would have to speak with my office manager Monday and whatever the handbook states they would have to follow. I already knew that they were going to try and screw me one way or another because 2 other employees just left and they refused to pay them. When Monday came around it was set to be my last week of work but at the end of the day I was told they would have to terminate my employment for giving out an employees phone number (with the employees permission) to another employee. At that point I asked again am I going to be paid out for the 10 days of unused vacation time and my boss stated that our handbook book clearly states that if an employee is terminated the unused vacation time is forfeited. I know they purposely fired me to get out of paying my unused vacation time. I was informed that the handbook is now being changed to take out the vacation time statement since every employee that has left before me and provided the 2 week notice has tried to receive payment from them and of course Noone has been paid. When they terminated me I didn't sign anything, there was no exit interview done and I was never given anything about my health insurance etc. I actually had to contact the company after all this because my paycheck was short and that was actually fixed, but not without a headache to get it fixed. I know the company has recently had financial issues but that is not my fault and makes me think that was even more of a reason to fire me to get out of paying and also for my paycheck error. If you could help me on what my next step should be I would appreciate it. I understand I am an at will employee so they can fire me at any time or any reason but does that change the fact that I provided my notice a week before and only after pushing this issue was I terminated?