Matt,

My daughters don't like this man and are VERY uncomfortable around him. My oldest will be able to get away by going to her boyfriends but my youngest will be stuck, not to mention I don't want anything to do with him or him anywhere near me or my family! How do I confront my W about this without making things even worse?

You really need to pay attention to your daughter's feelings about their grandfather. Children are pretty intuitive about these things.

When is FIL coming down? How long is FIL coming to stay with you? Are you able to get some time off from work so you can stay around the house?