It's good to vent, keep doing it.
In this case, it seems as though firing you was completely unfounded. I would seek for more clarity on the "why" part of their decision to let you go.
that being said . . . this is probably your only job reference and future companies will check with them before hiring you . . . be candid, but gentle in your dealings with this situation.
and i'm sorry, that seems unfair
Sweetpea