We had to do similarly for one of our cats. Grab the cat. Bend the head up. It will practically force the mouth open. Shove the pill deep into it. Close the mouth.
At least, at some point she learned to give up and stop resisting so damn hard every time.
Sorry for you, but how the fuck did you get like that ? If you aren't massively exaggerating, that sounds super un healthy and a massive mental issue. What can possibly make it become like that?