Father With Dementia

From before the time I was born, my father was a very observant religious man. He put on tefillin every day, went to shul regularly, studied Torah, and taught me to be who I am now. He was very kind and scrupulously observed every mitzvah he possibly could. Sadly, my father now has dementia. This has affected his personality. Today, my father rails against the very religious principles he once practiced. And he uses a lot of profanity in reference to the beliefs his demented mind has taken on. He says the most terrible things about G-d, the Torah, and Halacha. Anyone observing Jew would be disgusted by what he’s saying.
And he has stopped practicing too. During Shabbos, he turns lights on and off, watches TV, and makes phone calls. We have tried, but we can’t control him. He can be quite combative. If he was still driving, he’d be driving on Shabbos too. If he had access to food of his choice, he’d be eating treif.
My father now lives with us because he can no longer live by himself. We have hired part-time care for him so we can have our lives and our sanity. We like to have Shabbos guests. But when we have people over, we can’t stop him from behaving like this at the Shabbos table. Some of our friends understand the nature of his condition, but others cannot comprehend what’s really going on and think he is just a self-hating Jew. They do not realize what he was like in the past before he developed this irreversible condition.
We like having Shabbos guests over, but we find him an embarrassment. We don’t want to turn away anyone from our home. And we don’t want to exclude him either. How do you think we should manage this?