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.
If the honey is solid, then you should throw away the mouse as well as the surrounding area which you mostly believe was affected and benefit from the rest of the honey. If the honey is liquid, you should not utilize it and you have to discard it. This is the opinion of the majority of scholars. Shaykhul-Islaam Ibn Taymiyyah however, is of the view that it is permissible to utilize honey in this state unless it changes. Nevertheless, it is better and more cautious to adopt the opinion of the majority of scholars.