FMLA possible discrimination advice

Location: New Jersey – I left work one afternoon due to being screamed at by another employee, I live with Bipolar with manic & depressive episodes as well as severe anxiety, my fight or flight was triggered. I went home called my supervisor immediately. I requested to take 10 days for my mental health because i felt a full out crash out coming. I was granted the time off as well as having a hysterectomy on the 11th day after the hostile work enviroment. My FMLA company representative called me to let me know they were taking the mental health fmla case and just merging it to the hysterectomy case and that she would be reaching out to the doctors for paperwork. I was down in bed rotting for days. I did not check my work email as I really needed to be disconnected. I reciebved a letter stating my paperwork needed to be in by x date. HR said it needed to be in 10 days sooner than the document i had. The date HR stated was a sunday.. That monday at 11:30 my documents were in. The next day I received an email that they were ending my employment as i was out on unauthorized leave… Mind you i was a high performing employee for 11 years with no writeups. I asked HR to reconsider as my paperwork was in one day late beacuse it fell on a sunday even though my paperwork stated i still had 10 days for the deadline. Do you think i should persue legal representation? Or just move on and leave it in the past? I would hate to relive it all if theres no case there.