Not sure what this could mean

My HR told me they had requested a firm offer but was told "A request has been made to return your OF306 so that you can provide better detail for the reason you have marked “yes” for number 12. For example, were you fired, or did you quit after being told that you would be fired" I marked yes, and attempted to give detail but they only allow a certain amount of characters (like 15) which made it hard. Here is my situation which I passed on to HR via email: I was trying to explain that after making a complaint, the problem was never addressed and it became a really hostile environment. I told a supervisor I planned on leaving because of it.  A former coworker told me that my situation was not new and that I should start applying for unemployment because it can "take a while" and it was "just a matter of time" before they would let me go due to making a formal complaint to the state of Texas. After I was told that, I started the unemployment benefit process and was called by HR and offered a severance package and they told me they would not contest unemployment.  I was never told I was fired and had already informed supervision of my eventual plan to leave. So, as you can see it isn't very cut and dry. 

I am trying to be as honest and as transparent as possible so nothing bites me in the butt later. I have already sent this email, so I am really hoping I did the correct thing. If not, what can I do to fix it 😅