All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Our advice to you is to avoid Waswasah (obsessive whisperings).
Regarding your question, if the beef used in that fabric softener was transformed by Istihaalah (transformation), then it is pure according to the predominant opinion, and it does not make the body and clothes which it comes in contact with impure. Please refer to fatwa 313504.
For more benefit, please refer to fatwa 209290.
Allaah knows best.