There is no way that you should not invite your father.
Thimk of it this way, there are going to be alot of eyes on him, and alot of people talking to him that he isnt going to be able to drink as much till the very end. And then, that doesnt matter.
I have the same problem but its my mother in law, she hasnt come to reality that my father in law got re-married. they have been seperated for over 24 years and she has been with a new guy for 13. She does drink alot and doesnt relalize what she is saying till after, I got my finace to talk to her and tell her to tone it down, and we also talked and agreeded that if it gets to bad, that someone will ask her to leave. Its rude, but we spoke about it already.
And if that doesnt work, shoot up the prices of his drinks, too expencive to drink, then he wont drink alot.