Arctostaphylosglauca's journey

I recently gave my notice at my job as a marketing specialist at a mid-sized tech company. Unfortunately, my employer reacted poorly and told me to leave immediately. To make matters worse, they reached out to my references with a letter that misrepresented my time there and painted me in a negative light. I never expected them to go out of their way to damage my reputation like this. I'm really frustrated and unsure of how to handle it. I definitely won't be using them as a reference anymore, but I'm considering contacting my references to apologize and explain the situation. Has anyone else experienced something similar? What steps should I take next?