Has anyone dealt with your father coming on to you sexually? It's crazy insane. I'm so uncomfortable.

This is common with some types of dementia. The Alzheimer's Association has a toll free number and trained people answer the phone 24/7.
1-800-272-3900 and or alz.org is a place to start.
You can tell him that it is not appropriate for him to act the way he is. But this will get you no where given that he has dementia!
Is it possible to get someone in to help you? Another caregiver might help the situation.
Have you discussed this with his doctor? And is it something that adjusting medications might help?
The main thing is that you remain safe. If at any time you think you are not safe you have to make the tough decision that placing him in Memory Care might be the only solution.
Just remember that this is the disease, a broken brain, it is not a reflection on you or how he really feels about you.

There is a thread on this website where it is discussed - but I'm not sure where. Hopefully someone can link it here for you. How awful and frightening for you. Your father probably thinks you are your mother, maybe you have a strong resemblence to your mother when he first met her. Remind him you are his daughter. Stay safe. So sorry you are going through this.

Unfortunately this can happen with Dementia, especially Frontotemporal type I believe. This is hard. Have you spoken with anyone like your local Alzheimers/Dementia Association? They may have an experienced councellor to talk to for support or advice. It's OK to tell him "Dad it's not polite to say that" then change the subject. (((Hugs))))