she was garding your food, i would not let her sit anywhere near you. give her a chew or something and sent her to the door mat or in her bed or simply in a corner somewhere. but nowhere near you. Delta is a bit like that with our cat she will have a snap if the cat is getting to close to food that she wants where i am making it for her or not.
from what i have red about the bite your cant was in the wrong place, she was aiming fpr poor Meffy. not condoning it but i dont think it was deliberet that you got hurt.
i would recomed your teach her tolerance, feed Meffy first, give him a treat first, at toy first a chew first. make her sit and wait till he is finneshed or till you think seh is relaxed or behaving herself. keep her on a lead if you dont trust her. that way she cant do anything you dont want.
because of Echo's problems with Inca, it used to be if Inca even walked past a bone or toy Echo thaught was hers or didnt want her to have even though Echos wasnt playing with or chewing it, she would lonch herself at Inca, so if i braught out a bone i would make Echo sit and watch and know that I was choising to give MY bone to Inca, and did the same when we got Delta, it has worked so well withg Delta that i can get bothe Echo and Delta eating the same bone at the same time.
because of Meffys placid nature i would encorige her to see him as the leades (but your 2nd in comand as you are the utimet leader in the house)
another thing you can do is po a lead on her and set up a similer situation where you think with set of the same reaction. this way you know its coming and you already have the upper hand. if she tries to attac him again give her a sharp tug on the lean and tell her no or leave os something that she will; learn means to stop what she is doing.
please do take this the wrong way, i think you have just let yourself slip into a faulse sense of sicurity because she is a small fluffy breed compaired to your big strong boy who you know needed a firm hand. i think you may need to think of her as a bigger dog than she is, if you get what im saying. but i have no doubt that you will get it sorted. and i think Meffy will help with his calm nature.
good luck let us know how you get on.