Hello , In case of affirming a negative statement like the sentence you mentioned you use "neither" So in your example : I won't go tomorrow Me neither . * meaning "me too I won't go" I will go tomorrow would have the answer " me either " * meaning me too i will go " (here you are affirming a positive statement)

sorry to say, cherry, we never learnt "either" in english like what you told. as i know, too and either can both mean "also/as well" as adv. in the end of sentence. the difference is: too for possitive statement but either for the negative. eg. ---I'd like to have a rest. ---me too./I'd like, too. ---I can't swim. ---I can't, either. in the second conversation if we use neither instead, we have to say "Neither can I."...

Cherry, using "me either" after positive statements is incorrect! me either, me neither, nor me, I won't go either, neither I will go are all correct, however some of them are not grammatically correct but used a lot in spoken english.

'me either' is okay