How do I turn down my boss’ sexual advances without losing my job?

I am decent and hardworking. I don’t wear provocative outfits although i stay classy.

This my father’s age-mate has been on my neck for some time now just to go down with me. I keep telling him NO and all but he won’t bulge a bit. He’s got a wife and kids.

I don’t wanna ruin his home neither do I want to put my own future in jeopardy by sleeping with him.

However, jobs are very scarce in this country and I don’t wanna lose this 6-figure paying job cos he keeps threatening to lay me off if I don’t do his bidding..

What do I do?? please advice!!

I am so confused right now… I need people’s opinion.